I think that when he's on intimate book with more modern characters he's one of the best writers around. But at the time his Thor run was not very good, and that combined with event fatigue to generate a lot of hate for FI. I think that it would have been fine if FI had just been a Thor/Cap crossover, but people really didn't want to like it as a huge event. So there was enough negative stuff associated with him to get people to grab their pitch forks. What can you do? It's the internet.
It's died down a lot now that Hawkeye has reminded everyone how good he can be. We'll see how things go with his FF run.