What's the real advantage of filing AOS before FAD Is current if you don't need EAD & AP?

There's been a lot of excitement about the movement in the March Visa Bulletin, but I'm trying to understand how beneficial it really is for people with an approved I-140 who don't necessarily need EAD or Advance Parole and whose priority dates aren't current under the FAD chart. For example, F-1 students who are still several years away from graduating.

Since the I-485 won't actually be approved until the FAD becomes current (and no one really knows when that will happen) I'm wondering what the practical upside is to filing now. I understand there can be interim benefits, but filing AOS also formally declares immigrant intent, which could reduce flexibility in some situations.

Am I missing something? What’s the main advantage of filing now instead of just waiting until FAD is current?