I don't think his face 'fits' Moffat's "rewrite light" showrunner approach. Cornell is one of the people who - by his own admission - was heavily rewritten by RTD. He describes the first draft he got back of Human Nature/The Family of Blood from RTD as practically unrecognisable, for instance, but in a good way. This was how RTD rolled, and the only people who IIRC were allowed their own final drafts under RTD was Moffat & Chibnall. (Though several episodes passed RTD by during Series 3, including those Dalek episodes, when he was really very ill.)
Moffat tends to bring on experienced writers who work alone, basically, and doesn't much care if they have much Who experience. RTD in those early years almost exclusively bought on people who'd written for Who in other mediums in the off-air years (including Moffat), and Cornell was one of the key contributors to the Virgin New Adventures books. His TV work is actually rather scant besides; some episodes of Casualty, etc. As such Cornell isn't really necessarily a fit for Moffat's approach, but what is lost is that he's a magnificent ideas man with a brilliant compass for emotional stories.
He still plainly loves Who very much, blogs about it on his personal site, and has written/is writing a number of 11th/12th Doctor comics, if that tickles your fancy.