ORIGINAL: Mdkanz
I know lots of people that have never balanced 2s lipos.
Many people don't do it... doesn't mean they shouldn't do it. It's really up to each person but think of balancing as preventative maintenance. No two cells are exactly alike and will have slightly different charge and discharge rates. You may not see any problems until you're on your 50th charge but that doesn't mean it's not building up.
A balancer costs $20-$30 and doesn't add that much time to charging... the question shouldn't be: why do it? but why wouldn't you do it?