Returning to the OP...
As far as Tuvok. I found he could be very immature in his own way. The fact he was a senior officer being groomed to one day be a captain, he showed great selfishness when it came to many of the emotional issues when dealing with the crew. Many times Janeway had to order him to attend ships functions because its expected of senior officers. It reflects badly on the captain if her chief of security is unwilling to associate with his staff for moral support.
He also showed poor diplomatic skills when it came to dealing with Neelix. Nobody really liked Neelix when he first joined the crew but Janeway, yet they all were polite to him except Tuvok. Not very mature.
I wouldn't call Tuvok selfish
for behaving this way. He is just not very gregarious and does not like spending his free time with the rest of the crew. And I can't say I blame him--I wouldn't want to socialize with Paris, Kim, or Neelix myself.
In fact I would probably avoid them, just like Tuvok does. Just like Worf, come to think of it. Do you think Work is selfish, or that his behavior reflects poorly on Picard or Sisko? No--he just likes to be left alone.
And I would argue that Tuvok is
there for moral support when someone needs it. I can't name the episodes off the top of my head, but I'm pretty sure there are moments when Tuvok bonds with Neelix and helps out others, like B'Lanna, with meditation, etc.
He also offers council to Chakotay and generally treats him with respect. In fact, I would argue that he treats Chakotay better than Chakotay treats him. What does that say about his level of maturity?
Paris & Kim aren't any different than more than half us here.
I know--that's my problem with the characters. I guess I just don't like it when grown men act like teenage boys.