The reason being that Poser uses an internal Python version and they don't want us to install another version in our computers to avoid confusion. People would think Poser installs Python during its own installation, but no, it already comes with its own version built-in.
Well that explains a few things. I've always felt like I've found both python 2.6 and 2.7 stuff that seems to work in Poser. Now I know why I've never been able to figure out which version to use.
I like to program on an IDE and not a text editor. Ironically, I even bought a couple of Python books, but none of them worked, even in the simplest examples, because Python apparently couldn't care less for backwards compatibility.
I agree with you about preferring IDEs, but if you ever do decided to give Poser Python a go again, I recommend Sublime Text: The text editor you'll fall in love with As text editor's go it's pretty powerful. If you save the file you are working on as .py it starts color coding stuff for python. It's also great at autocomplete when it comes to dealing with a customer framework like Poser has. It's pretty smart at recommending stuff you've typed before so you usually only have to type in a method name once.
It also has a great feature where next to the scroll bar it shows a tiny version of the document with the part you are looking at highlighted. I love this for things like hand editing out the geometry in say a .pp2 file, because even though I can't read the text, I can easily see where the start and end of the geometry stuff is by the formatting and easily select and delete it out.
Also if you do want to try out python in Poser again, I highly recommend PhilC's Poser Python tutorial. Even though it was written for Poser 8, most of it still holds true, and he took the time to set up a good table of contents in the pdf, so when I'm looking up a Poser python method it's still way faster and easier to find it in his pdf, than the one SM gives us.
Python is one language I never took any classes in. I should try it some time, though I doubt I'd ever produce any Poser Python scripts.
Personally I hate Python. I get why Poser probably used it when it first came out, and why they've probably stuck with it, but I'm a strong typed girl and python is not. I'm told that for people who don't know any coding it's considered easy to learn. I think though you would pick up some bad habits learning that way (much like I did learning to program in BASIC, although to be fair OOP wasn't really a thing back then, at least not on the computer's I had access to). Still, there are some pretty cool little things you can do to make your Poser life easier if you pick up a bit of python.