It's all about risk. If you bet the whole draft on a QB you take a big risk on one player. If you stay put and use all the picks, you spread the risk out and will likely have some great players and a few that don't pan out. For this reason, it's easier to convince yourself to stay put and make the "safer bet." But the problem is, it's SO HARD to get an amazing QB. Unless you draft one, it's nearly impossible to get one.
I'm all for betting the draft on a QB if the team has confidence in the guy. Every other player on the team is important, but it's MUCH easier to find players to plug holes at every other position in creative ways....for instance we saw how Beane signed some quality "no-name" guys to fill spots on the team last year for reasonable prices. Also, every other position on the team is more interchangeable and can adapt to new schemes and such. Of course it would be great to have stars at every single position, but even if you lose those guys because they cost too much, they're much easier to replace than quarterbacks. It's important that a GM has this kind of sense.