I think the idea of evening out the teams is just to work-around the ever-changing server caps (IE: 80 on Knit, 80 on Bish, 60 on Rook... well have the server let 20 more players wanting to connect, just on Rook only). And in regards to maintaining the best quality of game play for a player while on the server, this does nothing, if anyhting it makes it worse and increases lag by pushing the server above it's limits (yes, the teams are even, but if you can't play then what's the point?).
I'm personaly unaware of what trips a server into lowering/raising it's maximum population numbers throughout the day, but if it were possible to eliminate it (or make it a rarer occurance, especialy during prime times when things are at their peak) then I think it would help eliminate some of the player frustration over it (obviously, not all of it).
Once a server is capped, it's capped, but if a server is capped at 200 players 24/7, then people learn to respect the hard-cap. A squad leader starting up for the evening, seeing the server at 190/200 and estimating 20 members in attendance for that evening, will make a decision to not join it and pick another server, knowing once it hits 200, it's full.
The way it is now, that squad leader shows up, picks a server that is 210/250 players, and then a short while later the server cap is lowered to 200, but there are still 230 players on it. This frustrates the people not only trying to connect to it ("WTF, it's got 30 players over-cap! My CO is going to have my hide.") but the people who already connected to it ("Worst attendance ever guys, there was just 3 of us on last night, thnx for blowing it off." - Is it really his fault that 10 minutes before meeting time the server cap changed? Hopefuly the rest of his guys locked out have a way of contacting him while he's in-game and can change to another server.... hopefuly.).