The 'cuteness' of his drawings -

I bet it's a big component of his success. Or at least, made his success bigger. It makes his work easier to digest. There're lots of ugly comics out that aren't as successful as Crumb. Admittedly there's more going for Crumb too; his work is humorous and self-deprecating without being self-destructive (that I can tell; not being a critic or psychologist). But, his comment at one point in the film where he says he picked up the 'cute' style while he worked at the greeting card co. and hasn't been able to shake it, and sounded irritated, just brought this aspect up. You can see where that'd be infuriating, as it would permanently 'nerf' your style when you might want to be taken seriously - yet, again I'm sure it's made his stuff digestible to a wider audience, contributing to his success. Whether he'd /choose/ that or not who can say?