Tuxedo Mask is there to provide moral and sometimes physical support to the girls. He gives advice (sometimes good and sometimes bad) he will often stand back and let the girls take control of a situation but when things get hairy he will also jump into the fray and do his best to help which is pretty brave of him considering how weak he is compared to Usagi and the others. In the original anime I don't think his character was written the best. I know Sailor Moon is all about girl power and that's great and is one of the reasons I love the show, but it would've been nice if Tux had been a bit of a stronger character and a bit more Usagi's equal. I would have liked to have seen him develop stronger powers. In the manga he does a little but never to the point where he becomes equally as powerful as the girls. And that becomes a sore point for him. He feels bad that he cannot help them more. He feels like he should be the one to protect them. His inability to be able to do that makes him feel like less than a man.
I don't have a problem with Tux swooping in to save Sailor Moon every once in a while. I know some people find it annoying especially when in the new anime it says in the opening song that they do not protection from men in the lyrics. But it's not like Sailor Moon is incapable of fighting on her own and needs saving every five minutes. Far from it. In the new anime she is ten times more brave and fit as a leader then she was in the older anime. There have been several moments in Sailor Moon Crystal when Usagi has really shocked me by being so confident and secure in herself as Sailor Moon. In the old anime she was frightened and cried a lot which was fine (but got old fast) it's nice to see her the complete opposite in the Sailor Moon Crystal.
One of the biggest criticisms about Tux is the difference in age between him and Usagi. He is 17 and she is 14. He is in high school and she is in junior high. I really get mad when people call him creepy, a pedophile, or a statutory rapist because of a measly THREE YEAR AGE DIFFERENCE. He is not a pedophile, for God's sake. There is nothing creepy or wrong about their relationship. Three years is a really small age gap. And the two of them do not even get serious and start having sex until way, way, later when both of them are older. This is not a 30 year old dating a teenager. It is a kid who is 3 years older. The fact that there are people out there who if this was a real life situation would report him to the police really, really, depresses me. They would destroy a young man's life over a stupid, tiny age gap. I'm pretty sure in a lot of places when the age gap between two kids is that small and that close that most police would've even charge the kids with anything. I think they're called Romeo and Juliet laws.
Now if you want to hear about a disturbing relationship then you should check out Cardcaptor Sakura. I love that anime but I've always been disturbed by the TEN YEAR OLD GIRL in that who is secretly engaged to her GROWN ADULT TEACHER. I mean seriously, what the hell? What sort of a grown man proposes to a ten year old girl? Now that is creepy and weird. Usagi and Tux are just a normal pair of kids.