Every single Vykker in MO spoke with a high-pitched voice - that's 39, so it seems pretty standard. The exception, of course, is Headley, but his description on Oddworld.com says he puts on a false accent. I personally think their current voices fit their appearance and personality like toe socks.
And I've nothing against any character having five fingers, in terms of character design, that's pretty unheard of. Even the Simpsons have four fingers, I mean, pfft, come on.
As for the top hats, I think it's pretty obvious they keep a chant suppresser up there.
