It's interesting how shortsighted people are when role switching is brought up. Role switching between raid nights, tiers or even expansions in raids, and the ability to switch roles freely for dungeons offers you a flexibility that we sacrifice in order to get to fulfill one role with whichever spec happens to the most suitable for it. Do people really fail to understand the difference between a Mage who in an ideal (to me) expansion would be swapping between all three specs on a fight per fight basis and a Moonkin whose adjustments total in swapping a few talents around? Who in turn can also simply go Bear or Tree for the sake of dungeons, questing, PvP and whatever else?
As much as Blizzard has tried in the past, WoW is still an MMORPG. The ease at which you can level and gear up alts doesn't change the fact that a lot of players, those who don't FotM reroll or are absolutely min/maxing players in a top world guild, end up more or less sticking with a 'main' character through their time of playing the game. If said character happens to be a Rogue or a Hunter who simply does too little DPS with all specs, then they're SOOL. Indeed, the only option they have is an entirely different character. How people fail to see the striking difference between this and swapping roles is beyond me.
But perhaps my casual friends and I are the odd old birds. Hell, I've declined guilds simply because some random person already had my name on their server