rokkolpo said:
you pay them.
and they use part of that money to make a bigger avatar (most likely) to make you stand out so that other people will also want that. it's not really an improvement to you, yet you paid for it.
Well, you don't get the bigger avatar automatically. You can still do any size you like, but it's just been put up to 100x100 for PubClub members.
I made it big because I like big avatars, that's basically it.
Besides, I don't really see the problem here. When you pay someone for something, in this case a subscription, how can you not expect to get something in return? It's hardly surreptitious or anything, it's just them holding their end of the deal. You pay for a subscription, you get extras in return.