I haven't yet tested the 3.5 Paladin. But yeah, it doesn't seem like much after the first few levels. I don't know if it's weak, but it certainly looks boring. Remove disease is a rather dull ability.
I recall that there are feats that let you use a Smite attempt to do something special. What about adding a bunch of feats that let you use a Remove Disease attempt to do something? Then you could give the Paladin a choice of one of these feats every five levels, or something like that. It would make it more flexible, a bit more powerful, without diluting the class' flavor.