Yea.
Also, new players are almost always either players who come from other FPS games or players who have accepted the idea that, in an FPS game, you are a guy with a gun. Tremulous is different. I remember that, as a complete n00b, I'd prefer playing humans because playing aliens was awkward and frustrating. This is, I think, true for most who are not at least moderately skilled in Trem. If you look at a typical public game in Trem today, people tend to prefer humans. This seems to make no sense since 1)aliens win most rounds, 2)winning is a big bulk of the fun, and 3)people play to have fun.
So there is some factor making people want to play humans rather than aliens. This factor should be (and is) counteracted by the high win rate of aliens. Having a balanced 50/50 win ratio between humans and aliens will (I predict) elevate the current preference for humans. Of course, as Ozzy said, you wont see this in MGDev every Saturday because experienced players often have small-to-nonexistent team preferences. It's more important to have even teams than to have equal advantage for each team.
The reason team balance is so important in other FPS games is because the teams are either identical or pretty damned near identical (e.g. same weapons and such). In the case of slightly different teams, one team might have a 12-round, 40 damage per hit, low firing rate pistol while the other team has a 20-round, 20 damage per hit, high firing rate pistol that's a bit more accurate. They're both pistols, and they are both used in fundamentally the same way. In Trem, however, you have two teams with the same objectives, but extremely different ways of carrying out those objectives. Why shouldn't they each have a different likelyhood of completing those objectives? Aliens is fun because it's easier to pwn with. Humans is fun because when you turn that corner, you know you are at a disadvantage to that goon. You are in a struggle to survive. You are nervous or afraid because that dretch knows exactly where you are, but you have no clue where it is. That's all Trem really needs.