nope.
Vogons wants to look like this.
not like subsilver

in this case the subsilver theme should be removed in the profil section

Probably, but I doubt Snover has either the time or inclination. I haven't seen him post much lately.

What's the matter with purple?

It's not the purple, it's the other changes that make this forum less usable than a standard phpBB install. For example, the message control icons at the top right of a message are so tiny and indistinct it's anyone's guess what they mean.

I agree that those are hard to see - I'm not sure why Snover made them that way. However, you can hover your mouse over them to see what they do.