It's not the problem with Groovy language itself. I think Groovy is good enough (and simple enough) for SmartThings' use case. It's just that you have to do things in SmartThings' web IDE (of course you can use some local IDE/editor and then copy paste to the web IDE in the end), and also work with SmartThings' APIs. The web IDE and the API documents are kind of hit or miss.