To me, it's mostly the fact that others are also not very firm in the idea. This is probably just a kneejerk from habit, since we haven't ranked a game this quickly since... SH2. And the only thing WA5 is better than P4 is exactly the time it had.
My point, though, is that P4 has a sensible reason for waiting - and I'd rather give it the waiting time, because I still don't feel comfortable with a fast ranking - I mean, why not give it another period so at least the spoilers settle down? It's mostly habit, but I like to think that giving things time to settle (even if only on a theoretical level) never hurts. That and I don't care about making segmented rankings. WA5, though, is just a matter of "just get in or die already", it had the time. I could also be swayed into abstaining on WA5 as well, but then I'd just abstain on this entire phase period.