The issue isn't that it's a simple min/maxing problem. The issue is the discrepancy between CoP and the other talents is in the neighborhood of 10 to 15%. That's massive. That's a drop very very few are willing to take unless they only raid LFR where DPS never matters in the least. That much of a drop is close to picking vs not picking a 100 talent at all.
It's also an issue because it's a forced playstyle shift with that discrepancy. If CoP, mastered, had a few % lead over the other talents, that would be fine. People could then just pick what they wanted and CoP rewarded extra attention. But when dot weaving, even screwed up, still outperforms the other talents by a significant amount while also flipping the spec's entire playstyle on its head, people are bound to be pissed off. There's no reason why there shouldn't be some variety and for people to pick their talent based on their preferred playstyle. A 10-15% gap though pretty much kills that. Blizzard has even admitted that the Shadow 100 talents are a balance wreck.
Most complaints you see about CoP aren't the damage, despite some of the comments in this thread. People aren't bitching about DPS. They're bitching about the playstyle they've loved for their Shadow for years and years, the default playstyle of the spec, being turned inside out because Blizzard's number team seemingly decided to take the last couple weeks of beta testing off.