It's not silly, it's economics.
About 4-5 years ago they were initially authorized to issue 2-year EAD cards, but for a couple years they wouldn't issue them, with USCIS itself expressing concern about the loss of revenue if people only pay the fee once every 2 years instead of every year (the authorization for 2-year EADs didn't include doubling the fee). And one of the Ombudsman's reports mentioned how their reliance on EAD and AP renewal fees created an incentive to delay I-485 cases in order to keep collecting the renewal fees. He was then instrumental in getting the EAD and AP renewals to be "free" (i.e. no extra charge beyond being embedded in the one-time I-485 fee).