The older WR brings experience and immediate impact. I doubt Dez Bryant has any more of an impact then Michael Crabtree has thus far.IDK why you are under the impression that teams let go of number 1 wide outs all willy nilly, but if you look this year it just isnt the case, A. Bryant and M. Floyd along with J. Avant. Those are not clear cut 1's in my book. A older receiver is not worth trading for when we have so many holes and a younger one can be taken with that pick. Another thing is if Dez will be long gone by 11-13 ish. who will take him?
Free agency will determine the priority of the draft but there is no doubt the LB corps will be a high priority if not the highest.
And the 3 WR FA's that you listed are better then what we have on the roster.