Most likely for the same reason you found. Once you know it, it's very easy to use, and it's available in most distributions (if not all). So both familiarity w

Most likely for the same reason you found. Once you know it, it's very easy to use, and it's available in most distributions (if not all). So both familiarity with Tcl, while having that ability to build out quick and stable GUI tests, including the lack of churn in the GUI framework. For myself, having to readapt to a GUI framework when I'm just trying to get something visual up and running to make life slightly easier, makes something like Tk much more beneficial for just getting work done. A bit ugly, but anyone technically inclined will figure it out quickly, without constantly having to change up libraries. I only speak for myself and put my 2 cents in, I don't speak for anyone else, but for general tooling targeted at developers it seems perfect.