It's a pleasure planet; a rest stop. It's there for people who want to RP to go and RP sailors on leave. People wanted it, people asked for it, Cryptic listened and implemented it. Not much to do there I hear but walk around and take in the sights. But then again, isn't that true of most leisure locations in reality?
It has to be there, its a big(ish) part of Star Trek lore. There may be something to do there at a higher level, or perhaps when expanded content comes. But for now it just wouldn't be Trek if you couldn't at least see it.