Not that there’s anything wrong with being conventionally attractive but it seems like without any real variation in faces and bodies (proportion being one indicator), the characters wound up looking very similar. It wouldn’t hurt much if Barry Allen had protuding cheekbones or if Tim Drake has prognathism or a protuding face.
That’s not a bad thing especially if you need other means of telling characters apart if accessories, height, hair colour and fashion sense don’t help much. Heck not even body types count much either. They may turn out homelier than they should be, even moreso than with their live action counterparts.
It’s also really useful if this was in black and white because that would mean having to pay more attention to how different a character should look. Haircuts aren’t enough, it’s got to do with being willing to play with facial proportions.
Keep in mind that even in black and white cartoonists will still stick to a template though bothering to differentiate characters’ faces is a good thing.