Lots of people have a pally because they're very useful for endgame activities. They're pretty much relegated to those tasks, for me. To say there isn't much variety in games... just isn't true. Any time I'm doing hell baal runs I tend to see every class at least once or twice. Granted, it skews towards pallies, but there is plenty of variety.
More people use enigma'd hammerdins for mf'ing and Baal runs because they are proven to be the most efficient. Smiters are proven to be the most efficient for uber runs. If Blizzard nerfed them, another single build would be widely claimed to be the most efficient, and then you'd have another build to bitch about needing nerfed. The key word here is efficient. People don't want to spend any longer than necessary mf'ing and key hunting and killing ubers, so can you really blame them for seeking out the most efficient method?
You could certainly argue that hammers need nerfed. I'd have to agree. But smiters? Come on now. Smiters can get ripped to shreds in no time in hell if you aren't careful, just like ANY class. Hell, even hammerdins can get torn apart quickly. It all comes down to gear, and any class can attain godly gear. Also, PVP balance is of little consequence to me; the game wasn't built around it, so I don't bother.
My main fun from the game comes playing the other classes and experimenting with unorthodox builds.