This is a great pick! The only argument against it is his position. However, given our inability to build an O line and the ramifications there of, I don't know how anyone could not be excited about getting the best interior lineman to come along in 2 decades.
As for the idea that Building a Defense is the most important thing a team can do, doesn't it make sense that stopping other teams Defenses is just as important? That being said, no player in this draft is as good at countering the other teams Defense as Nelson.