My group is apparently a bunch of freaks...
Balance is something I see discussed a LOT in forums, but it has never...honestly NEVER come up in any game I've run or played in, including some games with what are obviously huge balance issues.
Extreme Example: Gamma World (pre d20, pre goofy color-based success charts)....you rolled for your mutations...roll high enough and you could pick..roll REALLY high and you could pick TWO. You also could end up with weaknesses.
I rolled INSANE numbers...multiple 100s on d%. Since I could pick, I went through and saw things like Power XYZ was supremely powerful if and only if you also happened to have Power ABC...I picked multiple pairs of these.
In the end, my character if hit with any energy weapon could use the damage to heal, and anything left over could be fired as an attack. I also had Kinetic absorption, so NON-energy weapons would heal me. Only blades couldn't be absorbed, and they did HALF damage. If I got too low on hit points, my friends character would throw an energy grenade at me. If that couldn't be done, I had Life Leech which took points from everyone in an area and healed me...insane...completely broken.
My friend had as much of a hoot as I did, and his character had a few mind powers, and telekinetic flight...his character could only fly ten feet off the ground though, because he rolled Phobia:Heights. Eventually I found a Superman suit with technology that let ME fly...better than he could.
The fun came not from balanced characters/abilities, but from the scenarios and playing the role - his character was constantly rolling his eyes as my character did the wildest things...like when a leftover nuclear missile was headed toward our town, and I seriously considered flying at it and kicking it, just to see if I could absorb the power and fire it off into space.
My character was definitely more memorable, but we had exactly the same amount of fun, and at times my pal had more fun as it's sometimes easier to get into the role of a flawed character having to run around with this beast.
To me too much of the balance complaint from players seems to be rooted not truly in the need to have uniform contribution levels, but in a sort of competitive spirit in a game that in my opinion should be non-competitive. Why does it matter if your character is, all things considered, not as powerful as another's? Is your character just as INTERESTING/fun?
I DO get the need to have similar levels of action/attention/focus, but I don't think that arises from balance, or the way that 4e makes everyone roughly equal in COMBAT (which I oppose, but that's 40 different threads). It arises from a DM who plans adventures around the capabilities of his party.
And here is where my thoughts are WRONG. IF you are only going to play pre-published adventures, then maybe you do need combat balance, because a pre-published adventure (without alteration) probably doesn't have a chance for your claustrophobic expert on insects to shine.
Again, though...I just have never seen this come up in my groups, and the only factor that I can see that is different from other groups I've watched is that there's no clear competition between players.