Arcane already IS a raid spec. It's just that DPS meter watchers don't particularly like it.

Arcane is a reduction of overall DPS, however, it allows fantastic wonderful sustained burst (I know that's an oxymoron but wait) DPS that has its uses. It's lower damage over all, but it's faster damage, which can be important.

A good example is Prince, where most guilds try and burn him through phase 2 as fast as possible (with good reason). Pop arcane power and trinkets, go into Arcane Blast spam off a PoM to start it off, and you can do an insane amount of damage in 30 seconds or so. You can only sustain this about 45 seconds or so, depending on gear, but it's usually enough to get it over the hump. Just taking Kara into account, there's a few fights where this sort of Burst DPS could really help. Moroes, for taking down an add, Prince, as mentioned, Curator would be wonderful but he's arcane immune (but arcane spam CAN catch you up if you fall behind on the adds), Shade after he summons elementals, Nightbane, to force a phase change if your MT/healers are falling behind (this is forced, I know).

There's a certain playstyle to it that's more than just tank and spank. It's relying on your allies to do a little bit more when you don't need it so you can do a lot more when you do.

But it doesn't show up on the DPS charts, so people don't play it. *shrug*

Arcane gets Arcane Barrage - an spammable instant spell. Ramifications of that have not yet been explored.