Problem #1: The difficulty of the encounter should come from the encounter itself, and not from the class you're doing it with. There is no reason a tank and spank fight should be more difficult for an Affliction Warlock then it is for a Mage.
Problem #2: The rotation simply isn't feasible. Sure, on fights like Brutallus where you sit there for an entire encounter and really don't need to do anything but stare at your DOT timer Affliction is fine. Can you imagine doing a pre-nerf Kil'jaeden, or a pre-nerf 4 Horsemen? It's simply not going to happen. Any fight that requires you to do more then put 100% of your attention toward maintaining a seamless rotation is going to have significant troubles reducing downtime.
Problem #3: You should be properly compensated for your work. There is no reason I, as a long time Affliction Warlock, should be asked to put for significantly more effort then any other DPS class in the game, try and maintain a highly complex rotation that is excessively prone to error, and expected to use a melee pet that is not designed well or supported properly by the class, and then only do the same damage as someone else who can still play blind folded.
The rotation is far more complex then it needs to be, the rotation is far to prone to error, it doesn't reward us properly for its difficulty, and it simply isn't feasible on any fight that you'll need to do something other then focus intently on your dot timer.
I for one welcome a rotation that is more involved then me spamming Shadowbolt as it's something this class has done for 4 straight years with only a few exceptions (FSW, and Naxx where you could have wanded to do more dps). But when I'm killing Arthas for 300 days straight like I did with Illidan while I wait for Blizzard to get off their butts to give me something new to kill, I won't be sticking with a rotation or a spec that's going to get in the way of me enjoying 24, House, Prison Break, Monk, or Psych while the rest of the raid gets to watch it while we're showing Arthas who's boss.