I think theres a difference between playin a "hot" game and playing to inflict pain. There's a certain level which I don't mind having a hot gun pointed at me. However. When Engagements start getting close quartered, 490FPS is gonna hurt like a royal SOB. Thats were secondaries should definatly be used.
You have to remember with this is that people play airsoft for fun. Not to go out and get hurt (unless you have a fetish for that stuff.
Another thing is realism relies on who you play with. If you play with a bunch of guys who act like paintballers trying to charge across the field firing two guns at everything that twitches then yeah it's gonna suck if you want sim-like play. However if you play with teams that actually like sim's and conducting themselves as a combat-like unit then your gonna have fun.