It is true that we have been extremely slow to accept contributions. There are many causes for this, not the least of which is that we are a small team of maintainers working on a very large and ambitious project. Whatever the causes, it is something that I am committed to fixing. I'm working with the engineering manager on a new system of prioritization to burn down the backlog of PRs needing review (https://github.com/search?utf8=%E2%9C%93&q=user%3Aatom+is%3A...). We feel we've made some good progress because of it.
We took down the roadmap because it wasn't being maintained by the team anymore. (I'll amend the blog post to note that fact.) We felt that no roadmap is better than an incorrect one. The best we can offer right now for a public roadmap is what is currently being worked on by the official Atom maintainers. There is an easy GitHub search linked in the Atom FAQ on the subject (https://discuss.atom.io/t/is-there-an-atom-roadmap/21033). Longer term this is also something that we are going to be increasing transparency on.
Again, thank you for calling out these problems. Community contribution is important to us. We're having some growing pains right now, yes. We are committed to fixing them and I and the rest of the team hope that you and others with the same concerns will stick with us while we work out exactly how to fix them!