Two points.
Firstly the issue isn't really that people think Wilson should be a regular or anything. It's just that it doesn't make sense that we have been rejecting chances to send him on loan but won't give him any minutes ourselves, not even in the league cup.
Secondly the Shaw and Martial examples seem a bit disingenuous. They were both big money signings who were already playing regularly at other teams. Van Gaal would look silly if he paid so much for them and then didn't give them chances. It's his use of players from our own academy that is a causing a little bit of concern. Last season Januzaj, Wilson and Pereira got less minutes combined than Falcao. Three hugely promising players being held back by a washed-up loanee isn't the sort of thing United should be doing imo.