Seems fine to me... they just should not expect to sell many domains.
I wouldnt buy one, not just because .sucks... sucks as an extension but because its too damn expensive
the problem is that the high priced domains are purely used as defensive registrations - to keep others from buying them and harming the brand. If amazon is registering "amazon.sucks" it's not because they're going to set up a new commerce site on it - they're doing it to keep others from harming them with the .sucks version. There is no other benefit for those companies registering the domain - it's a "don't be harmed by not registering it before someone else" situation.
I see potential for a lawsuit or two based on this fact. A team of expensive lawyers and a sympathetic judge and this whole .sucks extension could be derailed with a big judgement.