Campbell has a great attitude, gives everything and is a flair player, everything that Walcott isn't.
As for Iwobi, Chamberlain and Gnabry, they are also players with potential but how many potentially good players do we need?
Surely it must be better for the club to have a true world class winger and a couple of younger players, than several of the same ability.
I can only think that of all of those players, Wenger rates Campbell the least.
I don't see the point in having Walcott, Chamberlain, Iwobi, Campbell, and Gnabry, we could sell Walcott and one of the others, and buy a proper winger.