But there are many somewhat shorter series that are excellent - Tad Williams' two main works for instance, on the one hand you have Memory, Sorrow and Thorn which is very much traditional epic fantasy but quite good in its genre, and then on the other hand there's the marvelous and far more original Otherland. I really like Jacqueline Carey's Kushiel series, too, or at least the first trilogy. There's R. Scott Bakker's trilogy, starting with The Darkness That Comes Before (which I must admit is still the only book in the trilogy that I've read, but it is quite good). C.S. Friedman's Coldfire trilogy is superb if you like dark fantasy (written long before "dark fantasy" became cool and tons of pulp was published in the genre, these past few years).

Those are all finished series of 3-4 books though, if you want longer series that are still ongoing (if that's what you meant by "commit to", then it looks like Brandon Sanderson is the only way to go. He seems to be one of the few who isn't scared off by what happened to Jordan and Martin.

And yes, if you see a "worrying trend" in Goodkind four books in, then I really recommend you stop reading. I still maintain that book six is something of an achievement in terms of writing a fantasy story in order to make an explicit political point - or put a different way, it's quite good propaganda (although the ending is ridiculous even by Goodkind standards). As a whole, though, the remainder of the series after book four is only at times as good as the first four (which weren't all that good to begin with), while the amount of political propaganda and downright preaching only increases, and most of the time not even as well-written as in book six.