Well, those articles are not what I expected. All points they decided to use Clojure, but it is not clear to me why it cannot be used with Eclipse, that runs in a JVM. I was looking for something like “our users want a prettier UI, Eclipse is ugly”. Or “Eclipse does not allow to do X”.
In short, the eclipse framework became a too big of a hurdle when it came to implementing new features and also when maintaining the tool. Upgrading it was also really painful, and we were stuck on a really old version.
It became a very large and unstable project, and a big time sink for us, so we started looking for new ideas.