I wouldn't say there is much pessimism in AI today. There should be a lot more pessimism to prevent a funding vacuum. I'd like for the early 90s to be the last AI winter, but I doubt it will be.
Actually the success of deep learning has made us very optimistic again. Just read this blog post: https://deepmind.com/blog there is a screenshot of environment that deepmind uses to train its agents. It's like science fiction that an algorithm can learn to behave in such rich 3d environment, but it works.
Also see the graphs for atari environments: many games are played by rl agents "at human-level or above".
