actually, I'd be willing to guess you aren't cooking them enough. may want to go hotter, or longer, or mix in some foil to help speed things along.
My first couple attempts at ribs were pretty much disasters because I was chasing the red herring known as LOW and SLOW. I spent all my time and effort trying to get the wsm to do something that it did not want to do, run below 225. it was very frustrating and the product I was producing was, according to my mother-in-law, some of the worst ribs ever (it didnt help that I was trying things out like maple bourbon and peach sauces).
I basically gave up, and if not for a couple of fortunate events I would have never figured ribs out.
1) I was visiting my parents in fla. The place they were renting had a large barrel grill. I threw caution to the wind, bought some baby backs, made a small fire on one side of the grill and smoked some really great ribs. I decided the spares were my problem.
2) back home I started smoking bb with some success because rather than measuring my dome temp, I took out a screw at the top cooking grate and found there was a bit of a difference between that and the dome, enough to make my cooking level below 200* at times when chasing LOW and SLOW. I started cooking the bb's with much more regular success.
3) I discovered this board and found that LOW and SLOW doesn't really do much for meat other than extend you cooking time*. I stopped fighting the wsm, and let it settle in where it wants around 250-270 (without water) and start using my head, cooking by feel rather than be time and temp. additionally, the nice people here gave me the confidence to apply my hard earned skills to spares. Posters like Kevin, let me know that if I applied what a knew about bb to spares I would be much happier with the product.
4) everything came together a our first real attempt a competition (we competed only once before under a different name). I cooked some spares, with a minion start, and tried to milk the ramp up as long as I could. The wsm eventually got up in the 300's, but after about 6 hours, when I could tug a bone and the meat was shredding apart and not just falling off the bone, I knew right away that this was my best cook yet. I was thinking to myself, that last year we didn't get any calls, but if these ribs don't get a call, then I might as well give up because I didn't see how it was possible to cook ribs better than these. At the awards they called 10 places, I was so confident that each time they called a place (like 10th) and it wasn't us, I said to my bro-in-law guess that means were at least 9th, and so on. I had a few doubts when they called 4th, but we ended up third and were majorly excited. We took home a nice trophy at our second time out.
sorry for the long story, but I hope it helps. I really wanted to illustrate how the wsm is a great cooker if you don't fight it, and that (IMO) good bbq comes from sound cooking knowledge and not some mystical ideals or old timer dogma.
*sure there are some benefits but as far as the wsm goes, they're way more benefits to not running LOW and SLOW (IMO)