Personally, I agree with Wenger. Having it count after extra time makes much more sense. In that way, for e.g. Monaco would be forced to come out to play before extra time.
The away goal is stupid because it takes away the importance of keeping a clean sheet away from home. Is 2-0 away really easier than 3-1?
http://www.theguardian.com/football/blog/2013/mar/13/the-question-football-away-goals