"...part of me looks at society as it is now and thinks we’ve been infantilised by our own taste. We’re essentially all consuming very childish things – comic books, superheroes… Adults are watching this stuff, and taking it seriously!"
Goodness, imagine that. People consuming works of the imagination, and having the nerve to take them seriously.
I leave myself open to the possibility that Brother Simon was grossly misquoted — note that ellipsis — or that the emphasis on his words was shifted to make it sound like he was condemning something he wasn't. But really, this is about as awful a piece of journalism as it gets. [Addendum: Pegg supplies more context on his own.]
Putting that aside, the idea that SF/fantasy/comics are infantalizing forces is beyond dumb. Why do they get singled out, and not stuff like Pitch Perfect 2 or Paul Blart: Mall Cop 2, arguably many orders of magnitude worse in such a vein? Because they come from that well of goodies we have tarred with the brush of being "kid's stuff", and because we reserve a peculiar sort of horror for socially retrograde behaviors that's out of proportion with their actual impact.
If anyone is likely to talk about infantilization around here, come to think of it, it's me, but I don't think comic books/SF/ponies are the culprits here. That they have manifest popularity is a symptom, not always of bad things. I grouse about how the recent wave of popular stuff is not the greatest creative role model, but I know better than to think it's a symptom of total societal decay or something. For that I would sooner look to the loathsome and violent behavior of mobs at sporting events or fraternities, which don't earn a fraction as much of the hand-wringing, pearl-clutching flabbergast as people dressing up as Tony Stark or Black Widow (or, for that matter, Inuyasha). And again, why? And again, because the former is allegedly "normal", and the latter not, and better the devil we know than the devil we don't know.