I'm guessing the initial capital investment for development of a groundbreaking motherboard is too high to justify the perceived risk to many board oems. AsRock does produce some interesting designs, but they don't carry their innovative features onto their total board stack, and the total execution of giving enthusiasts a really innovative and high-end offering has been (in my opinion) somewhat tepid.
With Ryzen offering real competition to Intel, I'd love to see *somebody* do a no-holds-barred, f*ck-the-price, push-the-envelope-all-the-way-out-the-other-side engineering showpiece gaming/server/workstation-ish mobo that focuses like a laser on putting the most ridiculous amount of computing speed and power into a mITX board possible, maximizing the utilization of available PCIe lanes, ruthlessly cutting or redesigning anything that takes up too much space (ATX 24-pin power connector, USB headers, DVI - I'm looking at you) and maximizing the space efficiency of everything else (SO-DIMM RAM slots, M.2 slots (storage), stacked SATA connectors?), even possibly using daughterboards like ASUS does. No superfluous g4m3r-y styling or loud colors, either, just basic black.
I won't be holding my breath.