I want a QB at 4 if one of them is there. That said, the Cowboys are going to the the favorites to win the East next year. From there, anything can happen, so it's not at all unheard of that we could go from 4-12 into contention. There's still a talent gap before we're realistically competing in the biggest games, but that can change quickly in the NFL.
As for the OP, we're not going to go 1-3 with Romo and Dez in the lineup, and if we did, there's not going to likely be a QB controversy, regardless, because we'll be getting good play at QB. I'd love to have the defensive help--and I won't complain if that's the route our board says to go--but it would be a mistake to pass up on the QB at four. Too expensive to get back there when you do need one. Too few legitimate options at QB2 out there now, and too high a chance Tony misses some games in the next two seasons. A deep QB corps gives us a much better chance of winning a few of those if Romo is out, and any one of them could be the difference between the playoffs and no playoffs. If Tony misses games, the backup QB will hands-down be more important than any defender we might be considering, and taking him now effectively saves what I'd at least hope would be two other first round picks in the next year or two when we have to get in position to move up and get somebody. Since there's zero sense in waiting until Tony retires to start preparing a QB, we're going to have to use our first round ammunition at some point during his window closing. Might as well do it now when we're fairly sure we can get it done and when we won't have to overpay.