Heh, there were nice Worf-centric episodes on both shows, and Worf's humour alone is of nice value, and Micheal Dorn delivers it in a perfect deadpan.
Also, on TNG Worf was very useful as a foil. He was the "we've considered the military/aggressive action, but we're not going to engage in it until we have sufficient reason to" in many briefing scenes.
Basically, he was there to allow other characters to give a reason why they don't "just kill/destroy/detain X", as some viewers would suggest. That's a very useful role, I think.
What do you mean by "politically correct"? I have trouble parsing it the context of Trek.
Controversial opinion of my own: I don't like Trip. Most ENT fans seem to gush over Trip, but I don't. I hate the way he talks: his extremely pronounced American accent is grating and the fact that Connor Trineer keeps his mouth open even when not talking even more so. Also, the character was irritating.
He's almost as bad as Wesley, so almost half as bad as Neelix and Michael Burnham.