There is absolutely nothing wrong with using a water pan...many do it and swear by it. However, as already mentioned here multiple times, it doesn't really add moisture to the meat, but rather provides a thermal mass to help regulate cooking temperature.
There is also another school of thought regarding water in a smoker: there's a belief by some that the moist environment produced by a water pan promotes more smoke particles adhering to the surface of the meat, which could improve the smoky flavor. I've never been too sure about the science of such a belief, but there are experienced pitmasters (such as Myron Mixon, for example) who swear by water smokers.
I say, if you use a water pan and get good results, keep doing it! Or, if you're unsure, try it both ways and decide for yourself which produces the best results for you. But as others have said, don't waste your time trying to infuse flavors in the meat with your water pan...that's just not gonna happen...
Happy Smoking!
Red