Drafting a QB in the second round only makes sense if we hit on a bunch of defensive players in FA. We need a DE (expensive), potentially two LBs (could be cheap), a safety (cheap-ish), and CB (expensive). We also need at least one new O-lineman (maybe two). We may even need a DT, depending on where you project Hand.
Even if Stafford isn't elite like we might desire, he's not exactly holding the team back (like pretty much all the rookie QBs this year). We could do a lot worse (and have). I'm totally fine with replacing him after his cap hit drops, but that's at least a couple years away. And we don't know what QBs will come out between now and then.
That's why it's a good idea to draft one sit the bench for two years and then see if it's still Matt or the other guy. AR sat awhile and they decided it was his time and let Favre go. And he was a hall of famer. All those others needs, no way we get all that in 1 year. More like 3-4 years and that's if it's done right.