When Being Wrong Just Isn't Enough

Ta-Nehisi Coates:

Was there something more Obama should have done to get a public option? Should he not have traded the Bush tax cuts for extending unemployment benefits? Did Obama settle too quickly on a small stimulus package? Was he wrong to allow the GOP to shut down planned parenthood in DC? Is the strategy of increased drone attacks in Pakistan inhumane? Was the financial reform bill he signed ultimately too weak?

I think all of this is fair game. I think Charles Ferguson's critique in Inside Job was really solid.  I think calling someone a "black mascot" or a "black puppet" because they don't agree with you is much less so. 

There is something I've never quite understood about the critics of Obama from the left: why is it necessary to portray him as a puppet of evil (if not evil itself)? You disagree with him on policy. Some of that disagreement is well founded. But that isn't enough. You can't just say "Obama is wrong". You have to say "Obama is evil."

Why?