I'm in the same camp as you, with Star Wars, I watch the cartoons as well as the movies, but I don't really read the books. I think the books and the comics are sort of suspended in a half-canon limbo zone, where the TV series can contradict the book/comic canon, but people still like to use semi-canon literature to find numbers or figures which don't interfere with the continuity of the main timeline. In my personal opinion, I don't think reading the books is necessary, because they inevitably may be overwritten and are not central to the story line, and any information which would be needed can just be accessed from this wiki.

I don't know about the quality and how well the books live up to the original feel of the stargate universe, but I think most of them are not published by the original studio nor are they really fact checked for canon by the original studio either (correct me if I'm mistaken though). If you really, really cannot resist and must experience all things relating to stargate, even if they are iffy on canon, then by all means, go for it. However, if you like stargate because of certain attributes that make it unique and stargate-y, then I suggest just reading the wiki or picking certain books that seriously interest you.