I would think any drummer worth his salt could play to a click...if not, how does he keep time anyway? He should at least be playing to a pulse in his head. If the bass player needs to listen to the drummer to keep time, he's already playing to a click of sorts...why can't the drummer do it? Shit I can play drums to a click, and I'm a guitar player! I hear a pulse in my head no matter what instrument I'm playing, that's how I keep time.
That being said, not every drummer is going to need one obviously, and not every song will either. Listening to some older bands, Zeppelin and the Stones what not, the tempo does change throughout the song, but it sounds right somehow. Ex: "Since I've Been Loving You"--that song continually slows down in tempo as it progresses, but I don't think it would sound as good if it didn't.