While MPC-HC is the best player on the market, getting the latest features first (PGS support comes in mind), the GUI is outdated. At it beginnings that was done to minimize sistem resource usage, on today`s modern sistems (P4 and above mostly) the impact of a new modern GUI would be minimal.
Also, a lot of people have started using MPC-HC as a external player from 7MC/MB & XMBC (my
HTPC Software Guide for Windows 7 Media Center also recommends MPC-HC as an external player for MKV), and the look of MPC-HC doesn`t really go to well with these modern HTPC front-ends.
I`ve done a mock-up (In Adobe Illustrator) of my ideea of a revamped GUI, with added buttons and menus for subtitle/audio tracks and chapter selection, the things a lot of people use the most.
If the developers are willing to start redesigning the GUI, i`ll be more than happy to do the entire design, everything from top to bottom, as they say.
Mock-up removed, V2 added