Neelix brought out a lot of Tuvok.
Kes shouldn't have been dumped over Kim as she was a much more interesting character, with her elven nature, telepathy and wacky biology that makes no fucking sense. People say she's underutilised, but that's not entirely true.
Kes pretty much had that love triangle arc throughout s1-2. And it's somewhat established in 'Caretaker' that Kes is an adventurous person with a rebellious streak. 'Darkling' and her not renewing her relationship with Neelix in 'Warlord' because she realised there's more to life than hedgehog sex show that, to an extent.
In fact if you look closely, you could see each season Kes is on as a 'decade' in her life, so she's maturing and changing somewhat every year.
Kes's problem is that she was written as a jack-of-all-trades character, which means she doesn't stand out as much as she should, considering her concept. She also got a lot of shit episodes in s1/s2 about her or built around her ('Elogium', 'Cold Fire', 'Parturition'). She's closer to Kim/Chakotay/Neelix tier, and not Doctor/7/Janeway tier because of that.