There's certainly something to be said for stable, uncomplicated and minimalist tooling that wont evolve out from under you and leave you with something that won't just-work five years from now.

I guess that's why Tcl is so popular in the EDA arena. I can stick some custom JTAG tooling in a Cyclone II design and talk to it by Tcl-scripting the 15-year-old software - and be confident that the same code (both in the FPGA and on the host computer) would work with the latest software and a current device.

Having said that, Tcl's not entirely free of compatibility and fragmentation frustrations: I sometimes wish that OpenOCD used full-fat Tcl rather than JimTcl, just so that I could make use of Tk. Being able to plot a histogram of data collected from the FPGA or make clickable buttons to trigger events is very useful.