If its up to me, there wont be a lot of improvemnts in Core in 4.6. The reason is simeple: WE need guidelines we all agree upon *above all*. I know talk is silver code is gold. But that is *the exact* reason drupal is so messy right now: Everyone opesn his PHP editor, codes away, focussing on speed, efficency and nice code. Which is good. But coders nearly always seem to forget to look at themeability and useability. Simply because its not in their line of interest (often)
I agree with the rest: guidelines are just that. In fact, I think that creating the HIG will be a lot of writing and not so much discussing, as we already have many unspoken rules about Drupal's UI which most long time contributors are aware of. It's only when new contributors arrive that they are often brought up. A HIG will help speed up UI development, as there will less "should I use A, B or C?" mucking about, and more time to implement advanced, elegant solutions. I also think that your current view of the average Drupal developer is a bit silly: most of the patches committed lately have involved at least some UI developments and improvements. In fact, I've noticed that aside from performance patches, the code structure is very rarely brought up in patch review, and the UI is the main discussion point. Plus, Drupal's UI is pretty darn good if you look at its power: services like blogger are aimed at one thing, and they do it very well. But as soon as your feature set becomes flexible, you can no longer discuss details such as "which checkbox should go first" as there are simply too many permutations to keep in mind. Juggling both flexibility and consistency is a tough job, which we have begun to tackle. Anecdote: I been doing some quick work on the fosdem developer room page on the fosdem site (they gave us a log-in). They use a CMS called Argon7, and trust me: the UI is lightyears behind Drupal. That is of course no reason to think our UI is "good enough", certainly not. But I think that you should realize that what is considered a bad UI today in Drupal would have been acceptable 2 years ago, and that is a very good thing. Our developers haven't gotten worse at UI design, our standards have simply gone up ;).. Steven Wittens