speaking for myself and vendors i know, many of us are interested in offering contests..... but vendors have their hands tied in terms of spontaneously sponsoring contests.
most of it is their fault - some used to post a contest every couple months to coincide with a product release, but it got out of hand when 3000 merchants all started contests with every single product, upcoming product announcement, product update, etc.

as much as i liked the old atmosphere of informal contests, and even informal advertising in the Poser forum and galleries, you really need to impose limits on things or they just get out of hand as people take advantage.