I too believe that a major effort to redesign the UI is anxiously expected and will be welcome all over the world. Just set a funding target, and publicly ask for donations (e.g. using: https://www.paypal.com/webapps/mpp/donations).
You will be amazed by the size of donations. See for example: I don't want donate you, because...
From all input I can get (by many Windows- and Linux-oriented geeks) UI is the most needed part of LO. The need for it has been hugely underestimated.
I agree you should act on it asap.
You could in parallel find some UI experts (in UI design & implementation) to propose design ideas and publish them for the users to vote on the UI design proposals.
Also set very specific hallmarks. No more than 6 months for alpha, 9 mo for beta, a year for final release.
Ideally the UI should be theme-based and modifiable (by experts, of course).
Why such simple actiion were not pushed forward yet?
I cannot accept that The Document Foundation is incapable to prepare and coordinate the UI upgrade project. It must be seen not as a difficult assignment, but rather as an opportunity: to refresh LO, provide momentum, increase user/organization adoption and interest, integrate features in an easily-accessible way, etc.