PulseAudio takes radically different approach to the problem than ALSA so just rewriting stuff isn't possible. I still don't understand why you think that ALSA API is the end of all Linux audio APIs. I mean seriously even if ALSA was extended so far that it would resemble the PulseAudio we have now its APIs would have probably changed completely anyway.
But the base argument is really simple: if a problem turns up in PA, should we replace it again instead of enhancing it? I say no. You seem to say yes.