Googles core focus is search, that's where they make their billions. as with all things Google, they throw out random projects see what works and run with it. media is not their core business, which is why they bought youtube. operating systems isn't their core business (yet), their music app sucks compared to most others. if you compare it to any mp3 player on the market its lagging way behind. they could probably care less about doing updates to the audio player. That's why the market comes into play, they provide core functions while developers can come in and design the fun stuff like media functions.
think of windows... their media functions are crappy, now think winamp, itune(crap), vlc, foobar, media monkey, and yes media center (came way after windows media player) they are better media players from 3rd parties. then you have audio enhancements like SRS audio sand box and foobars built in stuff, and winamps plugins.
there are audio companies I saw trying to get in on the android game, like SRS announcing getting into the android game and who knows maybe dolby will stick a finger or two, so im sure something will be coming out in the next year or so to fix this missing EQ.