Pretty much what kasperl said.
A scripting language could be used for other stuff (mission scripting comes to mind) but really, that's getting into an area that Ferrium should use. Trying to make missions scriptable with, say, Python while still retaining backwards compatibility sounds like a nightmare.
Depending on the language, it also opens the possiblity of security problems, ie viruses - mainly why I haven't made it possible to do things with a DLL.
If there's a scripting language that basically works mostly like C++ but lets you define the functions/globals, that'd be perfect, though (As long as it's easily integratable and doesn't need a lot of learning to use it).
And I hate "XML". I've heard so many people talking about how XML is great and mighty, but it isn't. AFAIK, it's just fancy HTML tags

. Not to mention the god-awful mess XML seems to make of website code. There's not much it has on the FS2 table format except it's more easily parsable by programs that were never meant to be reading the files in the first place, takes longer to edit with in Notepad, would take up more space, would probably require the inclusion of *another* library into FS2Open to do things properly, and not have as good a comment syntax.
Now that Microsoft Visual C's project files are in this awesome new language, I can't edit the damn things with anything
but that version of MSVC.

Goodbye, fixing ****ed-up project files.
So - I have yet to see some concrete benefit come out of using "XML", so I've been planning on sticking with the usual table syntax.