1. QB is the one exception, but maybe not the way you're thinking. QBs get overdrafted because they're in such great demand that if you don't overdraft them, you don't get one. If you're not going after a QB, you don't overvalue them on your board and it's unlikely they'll be BPA when your turn to draft comes around, because other teams will have them higher. If somehow a QB happens to be BPA when your pick comes around, you're looking to trade down. If you can't trade down for some reason, then you either take them or pass them up. But this will be extraordinarily rare.
2.. You are never set at OL. I can't believe people who have ever watched this team don't understand that. I believe you should be looking to draft OL every year.
Hey, it's possible for the draft to go badly. If you have a franchise QB, the clear BPA is a QB, and you for some reason can't find anyone to trade with you, well that stinks: the draft went badly for you. You take the next-best guy, but you don't pretend that it's not disappointing. This year, WR would be such a case. If the Cowboys have WR as the clear BPA in the first round and can't trade down, then they're very likely going to take a lesser player. And that's okay, but the reality is that the draft fell in a disappointing way. I can't think of a single position other than QB and WR that should give them pause though.
The big misunderstanding comes from this idea that we know what our needs will be in a year. Things change much faster than we expect. Guys fall apart suddenly. Guys develop suddenly. It's very hard to know what our needs will be even one year out. Given that, take the talent.