“Can I just not show up for my interview when I get the letter?”
You can do so. This will put the pause on your citizenship application as well because it will be considered ‘abandoned’ then if you won’t show up at the interview. However, you may also choose to go to your interview and tell the officer about withdrawing it. It’s not a problem. A lot of people change their mind at very last moment.
“What will this do to my application if I re-apply a few years from now?” + “If I withdraw my application, will there be an issue if I re-apply a few years from now?”
Abandonment or denial of a citizenship application won’t cause any problem to an applicant when s/he would file next citizenship application in the future. INS doesn’t keep the record of previously filed citizenship application as they throw it in the garbage after a year later, nor previously filed citizenship application influences a decision on a new application in any fashion even if INS would know about the previously filed application. So obviously, the question of having red flag in their computer system about it is completely out of question. Matter of fact, they don’t even ask whether or not applicant has previously filed for a citizenship application, nor this question is asked anywhere on a citizenship application for them to know.
“If I go ahead with the interview and get my U.S citizenship, can I give it up at any point later on?”
Yes. You can give it up anytime you want. But giving the US citizenship means-you cannot ask for US permanent residency as well unless you file for US permanent residency from the beginning.
“if I give up my U.S citizenship, then I will have no passport, and I will not be able to travel”
Yes. You won’t have a document to travel because you will be stateless until you would become a national of a country again.
“how can I become an Indian citizen again?”
Obtaining an Indian citizenship is not easy. You have to live 9 yrs in India before filing for naturalization there. I’m not sure whether this rule of living 9 yrs in India applies to former Indians, but I believe so. You would need to file naturalization application with Ministry of Home Affairs in Lok Nayak Bhavan in New Delhi. My uncle is a Deputy Secy. in Indian Citizenship Section with MHA. This office located on first floor and it is in Khan Market, close to Golf Link. If time will come, I would be able to help someone in this regard as I know many decision makers in that section.
“In their mind, they always felt I would go back, and to some degree I felt the same way too” + “I feel obligated to respect and consider my parents wishes”
If you are double-mined on obtaining US citizenship, AND feel that you would go back forever to your country then I guess you should withdraw your pending application for US citizenship. Further, it is more reasonable to back out of your decision of becoming a US citizen if you feel obligated to respect your parents’ wishes on this at this time.
“And after living here for all these years, I thought applying for the citizenship would be the right thing”
Just because you have been living here for so many years, doesn’t mean you should obtain US citizenship. Nor it is a matter of doing right thing. Rather the decision of becoming a US citizen depends on each person’s individual circumstances, such as some people like to sponsor their loved ones being a US citizen, while others want to immune themselves from deportation especially when immigration laws are kept getting tougher and tougher. I know so many people who are living here for more than 40 yrs, but they don’t want to become a US citizen. They are happy to be a permanent resident. So, the length of time living in this country has nothing to do with the decision of applying for US citizenship.
“I mainly wanted it so I could vote”
I know that you have mentioned other reasons as well to be a US citizen, but you have said that the MAIN reason for you to be a US citizen is-so that you could vote. Vote? Tell me you are kidding. You may say here about voting, but I’ve personally never heard an immigrant having becoming a US citizen mainly for voting right. You really made me laugh. Mostly immigrants don’t even care about voting in their home country, and you want me to believe that you want to be a US citizen so that you could vote in American election? When is the last time you have voted in your home country and how many times did you vote in your home country despite of living there whole your life (obviously after the voting age)? Anyway, it is your business, but I thought I should tell you that I’ve never heard any immigrant caring about voting in context of obtaining US citizenship.
However, if I were you, I would go for US citizenship for various reasons. First, being a US citizen, you would immune yourself from possible deportation in the future especially when immigration laws are getting tougher and tougher every day in respect of deporting an alien. I mean-you can never guarantee that you won’t get involved in a traffic accident or an argument with someone which might considered as a 3rd degree assault and a crime of domestic violence, which will make you deportable under immigration laws. Unless you don’t want to care about living here, you would try to immune yourself from any possible deportation. So, as a naturalized US Citizen, criminal infractions will not automatically result in deportation, as they may with a permanent resident
Second, since you travel a lot because of your job then it is more reasonable to have US citizenship. This way, not only you will save time and energy in dealing with those foreign embassies for a visa, but you would save a lot of money as well. Being a US citizen, you don’t need visa to most countries in the world, which means saving of tons of money and time/efforts in obtaining visa. Further, there is no guarantee foreign embassies will surely issue you a visa despite of having traveled to their countries many times in the past because they can still refuse a visa to you at anytime. But traveling on US passport means-no need to deal with those embassies anymore.
Third, the Internal Revenue Service in matters regarding inheritance and estate taxes treats US Citizens differently than permanent residents.
Fourth, retaining citizenship in your home country may involve continuing responsibilities regarding taxation or military service.
Fifth, worldwide protection to you from US government.
Sixth, of coursing voting right (your main reason to be a US citizen)

.
Seventh, there are many more advantages of being a US citizens, few of them are-be a juror in the criminal process, apply for employment in areas reserved for Citizens, and obtain a US passport.
In addition, don’t forget that you can easily obtain PIO thru Indian govt. after being a US citizen, and Indian govt. is going to allow dual citizenship very soon as it is a main talk right now in Indian Congress (Sansad-Parliament). I witnessed this as I'm in India right now. This way, you could have a dual citizenship in the future.
However, I just don’t understand that on one hand your parents allowed you to live here and make money while staying away from them, but on the other hand they are reluctant for you to get US citizenship. I’m totally lost here. Isn’t you are living away from them anyway for a long time? Besides, obtaining a US citizenship doesn’t mean that you will have to live here for your whole life, rather you could choose to live in India as long as you want unlike being a permanent resident.
Further, I don’t see Indian parents complaining when their sons go out with American women or change their name-from ‘Muhammad’ to Michael or Mike, or from ‘Shamshooding’ to Sam. Nor they mind when their daughters live without wearing Hijab in US, or their children live by American styles. Anyway, obtaining a US citizenship is a matter of personal choice. You need to evaluate your own personal and family circumstances before deciding what is best for you.
Good Luck.