Tcl is more-or-less required if you're involved with the physical design of silicon (most EDA tools only provide a Tcl interface). It's a good fit for that purpose. If you need a language which is easy to embed and you want non-programmers to be able to use it, Tcl is a good choice, though I've heard that Lua has supplanted Tcl for that purpose.
Our flow is thousands of lines of Tcl code around all the cadence and synopsys tools. Then we write more Tcl to create the power grid, create blockages, etc.
In the silicon industry it’s definitely tcl only. Zero Lua. But every tcl script I have seen is extremely simple, often just a bunch of commands to the EDA tool that reads like a list of bash commands.
Tcl scripting gets more interesting when you want to talk to a design running in an FPGA over JTAG. I have a toy CPU project which I've so far tested on Altera/Intel, Xilinx and Lattice FPGAs, and a debug interface where a C-based ncurses debugger connects over TCP/IP to a Tcl bridge which talks to the appropriate JTAG interface for the particular type of chip.
I'm also a big fan of the full-fat Tk-capable Tcl in Altera's SignalTap / Virtual JTAG - I used it recently to plot histograms on-demand for profiling RAM / Cache accesses.
I dropped Perl for TCL decades ago, after I realized that I could read and understand my TCL code months after I’d written it, but my Perl code was totally opaque.
But to be honest, while I feel like Perl has a lot of advantages (full perlre, full access to POSIX APIs, slightly better performance), I still can't look at it and keep my last meal down. Tcl having an event loop and Tk being native are pretty nice too.
I first encountered Tcl when trying to use the network simulator, ns2. Any language that lends itself to such hideous code can't be good, I thought, and stayed clear of it ever since.
I can't speak for other scripting languages, but it's absurdly easy both to embed Tcl as an interpreter in a larger project, and to create a Tcl extension which implements your own commands.
Sorry, missed this at the time. But I did say I can't speak for other scripting languages. All I can say is that it was much easier than I was expecting!