Probably because accepted standards are very hard to move away from, just look at the piston-based internal combustion engine which was developed in 1858(!); it's estimated that by 2040, 90% of new cars will STILL have one. Without some organization like the Electronic Industries Alliance or Consumer Electronics Association stepping in and dictating a new standard like they do for HDMI, or market leaders gathering and creating their own alliance, it's highly unlikely it will ever change.