I'm convinced that Whinter would be gone after trading down. You can NOT be sure Whitner would be available several picks later and need to realize that Marv & Co didn't want to risk losing the player they like.
DE and LE are not the most important needs (S, OT, DT) of our team. If Marv has done this, you all would have criticised his decision the way you criticise Whitner. You may also include "quantity over quality??", "ignore team's need", and "waste a 1st round on a possible backup" in your statements.
In short, no matter what Marv did, it wouldn't satisfy all the fans. Some fans will always find things to criticise and believe they know more football than NFL GMs, coaches, and scouts.