I like the mix-and-match at the player level philosophy Next is espousing (we'll see how it goes), although I definitely understand [MENTION=91812]ForeverSlayer[/MENTION] and the problems that can come from certain ingredients being added.
In a not-4e example, players can easily build a group-buffer or someone who conjures a swarm of pets in 3.x/PF. These are character archetypes some people enjoy playing and, in theory, the game is made better by their inclusion.
In practice, the group-buffer puts a load on the other players to keep track of all the modifiers. So one player gets to play what they want at the expense of making the game more complicated for everyone else.
Similarly, a conjurer can easily slow any battle to a crawl. It's a fun archetype, but I don't want to GM those battles and my other players don't want to play in them.
Every character brought into the game changes brings baggage that effects the whole game, not just their player. "Options for everyone!" sounds very noble, but a few bad options can really spoil the whole batch.
Cheers!
Kinak