In terms for usability for modders/developers I see the the interface as the most outdated part of the engine.
It's not impossible to have nice menus, but it sure takes a lot of work.
A long time ago I suggested an imrpovement to taylor. (Actually it was for more. We wanted to use it for comic cutscenes back then.)
I suggested supporting Flash. That was a long time before I ever heard of Scaleform or GameSWF.
Due to some issues (I recall licensing issues) it was never realized.
I'm not going to suggest the same thing again.
An even more powerful and flexible solution would be to embed a HTML rendering engine.
http://www.gamedev.net/community/forums/topic.asp?topic_id=527416Imagine the possibilities! You could finally put together option menues in any way you want. You could use JavaScript to interact with users. Menus and screens could be easily extended and many many people have enough knowledge of HTML to create great menus.
You could even have online news about the project in the menu, or check the current version of your mod/game and tell them about updates.
This would also be the first step to get rid of our menu inconsistency. Some options are in the game, some are in the launcher. It's confusing for new players.
I guess it's a lot of work, but I thought I should at least suggest it.
If you have any concerns about this, or maybe even completely different ideas, I'd love to hear them.