Question: I seem to have noticed that in the files "Lisp" original Autodesk (see also ExpressTools) does not makes heavy use of recursion. This is due to the lack of skill of the Autodesk programmers?
I would really not know, but I doubt it's a case of not knowing recursion. It's probably more a case of knowing iteration better.
Same principle as you can see a C++ programmer declaring & initializing local variables needlessly in a functional program. That's also quite prevalent in the express tools. It doesn't mean they don't know how to use functional programming, it's more a case of they know imperative a lot better and are used to variable declaration & initialization at the start of the function (which is generally a good idea in languages like C++).
That code of mine is also written more imperatively centric, since then I've learnt to embrace the functional way a lot more. And in lisp it's not extremely bad to go with functional and/or recursive, it's sometimes not even less efficient than an imperative & iterative method. Not to mention, the time you waste in typing all the code and then debugging the inevitable typo is greatly reduced when using recursion / functional.
You and me are in the same boat about recursion though. I know how, it's just that the recursive solution isn't the first one I think of. My mind seems to be iterative - but perhaps since I come from a C++/Pascal/Delphi/Java background. What i do miss greatly in AutoLisp is Object Orientation - sometimes that can also reduce coding a lot and make your programs a lot more robust.