How can you write Campbell Welbeck and Gnabry out of the discussion because you think they're not good enough to warrant it, but then include Arteta and Flamini?
I'm not arguing that we don't need a better striker, but If one of our forward players gets injured, we have various options for cover, plus plenty of creativity throughout the midfield to try to ride out a bad spell. Whereas our only properly defensive-minded CMs are Flamini and Coq. Flamini is hopefully and probably on his way out, leaving just coquelin. Even if you argue that Arteta could play deep against lower teams, we still have a much more severe lack of quality at DM than we do in attacking positions.
Anyway I'd say both positions are important to any title aspirations really.