First things first Adware is not Spyware.
Now on to the more important matter: the client has ads yes, but few don\'t these days. If you are unhappy with the ads then download PS and uninstall the client. Not to hard really.
If you want to know why the BitTorrent Client\'s designers put adware in it, might I suggest asking them? Since we -and the developers- have no controll over other peoples merchandise.
I agree with you that adware is annoying but there is little that can be done short of making your own client and hoping that it workes better (or at least as well as) this one.