Neelix' development is fleshed out in "Fair Trade", about how he has to learn to let go of his past insecurities and leartn to have faith in himself and in the surrogate family he's made on Voyager. His comic relief is only a mask that hides a sole that desperate to be needed because he's terrified of being alone. IMO I think many fans missed out of Neelix' development because of the bias against him. They turned their backs on him and didn't care to learn what he was really about to care about his development but it was there. Duie to Neelix' mistake of abandoning his people during war (Jatrel), Neelix now stands up anmd fights for them in "Homesteafd". That alone shows development by learning from a mistake.
Especially Neelix. I love this character and I have always see him as a tragic character instead of comic relief.