Back in BC level raids, on trash even as Affliction spec, the best dps was instant Corruption followed by S.Bolt spam, on fast to die trash type mobs. This was true in instances as well. If you do not have Corruption procs insta-bolts via Nightfall, then straight DD spam will be better then dots.

I'm not sure if Wrath dots are powerful enough to be higher dps, when the dot is only allowed to tick for 20-25% of its duration before the mob dies. I suspect, with only partial damage from your dots, like BC, you're better off with DD spam.

When it comes to bosses, or any mob who will be around for long enough to have your dots actually tick their duration and need to be reapplied, your dot rotation will be the dps method of choice.
You still have phenominal AoE as a warlock, any time you can Seed of Destruction spam on trash, the other toons will be wondering how to keep up with your dps.
Affliction brings extremely low maintanence, compared to other warlocks.. but in a high dps group, if you want to be competitive while leveling or in instances, more of a pew-pew spec might be better.