The main motivation (from my pov) is that we use Exposed internally in JetBrains for our needs, so we try to develop our own needed features and then look to a feature request at GH. At the moment Exposed covers most of our use-cases so it's not in very active development state, but we have contributors (e.g. PL for Oracle support
https://github.com/JetBrains/Exposed/pull/62) 😄