Interestingly I was just talking to R&D about this!
To get a good integration is actually quite a lot of work - particularly if you want it to be deeply embedded with the tools. SKILL is a bit different from many other languages because you really want to ensure that you can interact with the running tool, rather than the more conventional code/compile/debug loop you have with many other languages. So for example, we have added specific plugins to the new SKILL IDE to do things like Pcell debugging, abutment debugging, and CDF debugging. Of course none of this is impossible with a groovy tool like light table, so maybe for the future!