How riot balances champions to keep the player base happy

Well, it really isn't wrong, but it's arguably just for meeting player's constantly-volatile demands. I've slagged Riot off in the past for poor balancing (See Lee Sin and the early part of this pre-season), but in their defense, it's kinda hard when players demand you nerf Rengar one day and then demand you buff him the next, and demand you release a new skin for Morgana then whine that Lissandra didn't get a skin instead.