The interesting point is that what you call "internal implementation details" is much _more_ exposed with the OSS emulation in the kernel _enabled_.
Why?
Linux software not supporting ALSA has becoming quite esoteric.
But software like mplayer supporting both and trying OSS first and software supporting both and letting the user choose is today much more common. And that's exactly the case where users run into the results of the "internal implementation detail" that their application used the in-kernel OSS emulation instead of ALSA resulting in exactly these problems.
There is also a userspace OSS emulation for ALSA not suffering from these
problems.
It's not my decision whether or not to remove the in-kernel OSS
emulation, all I'm saying is that removing it might actually result in
less users having problems.