Charles’ frumpy clothes are perfect for an old-money Oxbridge nerd, but also help to highlight the differences between himself and Erik. As opposing forces, even their mutant powers clash: mental and physical. Charles cares far less about his image than Erik, partly because he can always tell what people think of him anyway, and partly because he was born rich and has the luxury of looking like crap and getting away with it. Posh Oxbridge professors can dress in rags because everyone knows that they’re posh Oxbridge professors already. Also, they’re above such frivolous things as fashion. Whereas Erik wants people to respect and envy him for his appearance, and takes enormous pride in his self-control and physical abilities. We do see Charles wearing three-piece suits, but that’s because it’s the 1960s when that kind of thing was the norm for businesslike occasions, and they’re never as sleek or trendy as Erik’s. — The costumes of X-Men: First Class, Part 2: Menswear.