It's ironic that it's the TF2 server that now has this feature as all the other valve/source games I have played on node are lone wolf type games like CS, DOD, DOD:S and CS:S.. and TF2 is the one that involves more of a co-op aspect (medics etc), perfect for playing with friends. And now you can't do that 50% of the time because the server wants to tell you who you can and can't play with. In my 10 odd years of gaming I've never seen anything like it.
Unbalanced teams are an issue in any of these games and always will be. All you can do is enforce that the number of players on each team is even, it's not possible to regulate how much talent/skill is on a team at any given time. Already TF2 has this auto scramble thing half way into a map, if it's been too one sided. That's already alot more than these other games have. Yet all of these games seem to manage fine already.. for years and years.
I don't know why some people get so obsessed with winning in "pub" though. Ever been on a CS:S team that is blatantly dominating? It's hard to even have someone to kill. It goes both ways but it's just a part of it. Sometime's the games will be great, other times they will be unbalanced. No one wants to be on a team where they have to try and kill 5 people at once (no chance) and in TF2 as Engineer in particular, it can be frustrating but no matter what anyone says or does, being beaten in something competitive will always be frustrating.
Some games are good, and even and balanced. Some games are not. Such is life.
My main point I want to make though is the type of people who are prone to complaining about "stacking" or uneven teams:-
Alot of them aren't good players to begin with and play with alot of frustration and in these cases, they will never be happy. For example, you can be on a bad CS team but still maintain a 1-1 k:d ratio.. like a 10-10 score, but not if you are swearing and throwing your arms in the air and blaming it all on the teams. I have been on TF2 teams where all the "good players" are on that team and they still get steamrolled. There is so much that is out of one's control like the classes everyone chooses, and whether or not people are AFK, it's very random and that's what makes multiplayer gaming exciting. The unpredictability of real human players.
Being on a bad team is frustrating for any game but for TF2 specifically I don't care about winning or losing so much, but if I join a server because certain people are playing, I want the ability to be able to play with them! Very frustrating. Servers 14 and 25 on Node have a big social/community aspect and these new server settings hamper that.