>In IronPython, you can just call sys.exit() to immediately force quit your script
That's because it is Iron Python, and not the main script engine of HFSS. Yes, maybe it works in IP... but it requires learning the already extinct and ABANDONED language, which would not be used anywhere else, and which interacts with external procedure calls for commanding HFSS. In what part is it better than making external calls in MATLAB or Octave?
Besides that, in principle I refuse dealing with any language where the accidental whitespace may affect the program flow. And I am not alone in this believe.

>In Vbs, this is easier, as you can use a GoTo statement
That's a good point. A good old forgotten technique... occasionally causing unrecoverable process errors. But it realy should not leak beyond the interpreter space, which is cleared every time you stop the script.