IMHO, what makes the user thinks at first that Inkscape is not so user-friendly, are the icons : they are not looking very nice (may be the black border around all of them could be reduced, to make them look brighter),
But we DON'T have any border around icons. Especiilly "black border." Can you better explain what you mean, with a screenshot maybe?
I'm pretty sure that a nicer icon set would greatly improve user experience and usability feeling, without changing anything else. I fully agree with you when you say that inkscape UI follow mental process ("I want it blue, blue is color, gimme the color thing!" ), and it would be even more the case with nicely designed icons, so you don't have to look around to find the "color thing".
I would agree with that. Some icons are decent and some are ugly, and they all certainly lack unity. But hey, this is exactly the place where an artist could help the project! Just grab share/icons/icons.svg and draw.
Now, if you draw just one or two icons and they are definitely better than what we have now, that would be a good contribution already. But the really huge and long-standing contribution would be to draw the entire icons set in one common style. If you can draw (and enjoy drawing) very clean, artsy, and cool icons, you may be qualified for the task. Personally, I like Macromedia icons that they have in their products - they are really tastefully done.
Drawing an entire icon set for Inkscape is a major artistic challenge, so don't think of it if you can't spend ample time working on the project. Also be prepared to fight with nasty critics (such as myself), and to give in sometimes and make the requested change if the consensus seems to be that a change is needed. And to maintain your work for at least some time, making new icons and responding to requests from users. But for all this, you will enjoy quite some fame, your work being prominently featured on thousands of desktops all over the world, and on many screenshots all over the net! :)
If you are interested, just do a few sample icons and post them here for discussion.