No, no, no and no. First of all, if you take him, what do you do with Taco? Guy comes in as a project player, just begins to show something, now he's relegated to second string (because you have to play someone like Chubb right away if you gave up that much for him). So you basically give up on your first pick from one year ago. Wow, that's the way to draft, eh?
And it's not 1991, the team isn't one impact defensive player away from a SB contender, there's multiple areas of need, limited depth in several areas as well.
I think the Cowboys should stick at 19 for their first pick, I don't subscribe to the "there's really only 14 top picks", there will be a top player available at 19, I've never seen a draft that didn't have a run on certain positions. Some position that the Cowboys can use will be there at 19. Since they have 2 fourth round and 3 sixth round picks, the better choice is to package maybe one of their fourth rounders and two of the sixth rounders (assuming some other team will do that, of course) and get another early 4th rounder. After the 4th the talent begins to drop off quite a bit, don't really see that a bunch of 6th rounders is likely to greatly improve the team...