You don't pick your attackers based on their defensive contribution.
Pardew, however, does exactly that and that's why we see strikers being played on the wing because they run a lot, Jonas being given more pitch time than he deserved despite zero attacking product, Ameobi starting games for his ability to defend set pieces, a plethora of full backs being (mis)used due to their versatility on the flanks and, yes, our most talented player being dropped and frozen out for being an attacker and not a defender.
It's going to be interesting to see how De Jong plays next season. If he's in the midfield strata it'll be telling to see his position when the opposition have the ball. I can see him being asked to drop and get behind the ball, much like our 'wingers' are asked to do and our striker will again remain isolated. We'll cross that bridge when we come to it anyway.