ALSA not playing either means that there are driver issues - and i highly doubt Haiku solves the problem of drivers having bugs - or there is some configuration issue.

But this (configuration) issue and the desktop focus do not seem to require getting rid of the entire kernel and - most importantly - the systems it supports. If X11 doesn't do (which i doubt, X11 ran on way more restricted hardware than what is available even on $5 "computers" today, but lets roll with it) you could simply write a new window system from scratch and provide a layer for everything you may think a desktop system needs so that any application written on that layer will keep working if the backend library/tech changes.

And from my understanding of Haiku, this is basically what happens already (<Stuff>Kit depends on some popular open source library for <Stuff> that is already available on Linux but exposed to applications through the <Stuff>Kit API), except with a kernel that doesn't support most things that people need today.

Personally i like the idea of Haiku as a desktop focused system, i just do not see what exactly having a custom kernel with its own need for drivers and hardware compatibility provide that a layer on top of kernel that exposes a similar API doesn't (beyond of course the hack value and the fun of making a kernel - something i am 100% totally behind as i personally write a lot of stuff just for the fun of it).