[[Please redistribute wherever appropriate.]] Why you should not use Tcl Richard Stallman, GNU Project As interest builds in extensible application programs and tools, and some programmers are tempted to use Tcl, we should not forget the lessons learned from the first widely used extensible text editor--Emacs. The principal lesson of Emacs is that a language for extensions should not be a mere "extension language". It should be a real programming language, designed for writing and maintaining substantial programs. Because people will want to do that! Extensions are often large, complex programs in their own right, and the people who write them deserve the same facilities that other programmers rely on.And so on. If you have nothing else to do, read this thread and see on this Wiki why Tcl is alive and well 12 years later ...(Btw., John Ousterhout's answer followed two days later in this thread as post number 71)RLH Lo these many years later... I read that and think he was an arse for posting that and I wasn't even programming then.
This link  is titled Your Ignorance Does Not Make a Programming Language Suck.
CGM See also Thomas Lord's 'An Account of Tcl War'