Making and playing Alts is a fun aspect of the game, and extends the life of WoW as there is always something new to try. Part of the fun of alts, and one of the perks, is you can get yourself access to more professions and the benefits they bring, and so between your characters, you can become quite self sufficient. It also acts as an incentive to work together with friends/guildies. In small guilds, it is rewarding to be able to cover every professions between 2-4 players and feels like you are helping each other out. As a last resort, all services can be paid for with gold and use of the AH.
Yet from one GC's latest tweets, he seems to think there is something wrong with this setup. Surely if we could have every profession on every character this would be a ridiculous simplification of the game. Not to mention the profession perks would have to be reduced or even removed. And would everyone have engineering gadgets?