Yeah, it is pretty experimental. Tables.kt has a different target. Like KMath it is a glue library that aims to provide a lightweight, but universal multipatform API to work with table data. It is not intended for heavy pandas-like column operations, but instead it provides clean interfaces and integrations with different sources. For example, we already have Exposed - based integration with DB. Also it is multiplatform.
I've actually tried to deprecate it in favor of DataFrame, but found out that DataFrame does not cover our use cases in terms of flexibility.