IMO, there isn't much of a problem in Teamswitching on insurgency, but
ONLY IF THE PLAYER DOES NOT SUPPLY "INTEL" TO THE TEAM! In AAS, I always try to teamswitch on the beginning of the round or as soon as I join. If I can't, too bad, both teams are equally balanced (only tactics differ). I don't really care if my team is losing or not (come on, Friday I played like 3 or 4 continuous rounds where the Americans got pwned every single round...). It is hella fun, seriously.
Well, as I normally SL I don't care which team I'm in. I'll be honest, I always try to teamswitch to the US side (as an american I like to be american. Sue me.) BUT if I spawn, I don't teamswitch. Period.
Even in insurgency as an insurgent when I can't (or don't want to) switch to the US side, I have a lot of fun hiding from an UB33R 1337 2 men squad and knife them
And molotovs are cool. So are IEDing APCs. Sneaking and scaring 'em.
And insurgents win 90% of the time. I still like to play BLUFOR though.
On russian maps I don't really care... On Fools Road the Chechens have technicals, but so what? Make a mech inf!