There comes a point where you experience overload of options however. My elven rogue may have combed over various dozens of various options and optional rules, creating weird synergies that break the game. Its customization as all get, but its really easy to make very broken characters by picking the right variant racial abilities, class features and archetypes, talents/powers/quirks, feats, and magical junk (not to mention spells or skills) to hyperspecialize and break what balance there is.
Though 4th edition DnD had a huge amount of customization for characters, in class, race, theme, background, paragon path, epic destiny... it didn't have very many "break the game" combos. What few popped up, most got errata'd out. The power level across the board was fairly even. Granted, there's a pretty wide range of power between a binder and a wizard, but it wasn't as dramatic as the predecessor edition. So I don't really buy into the belief that customization should be sacrificed in order to make sure stuff is balanced.