I really wish we could find some "HD" voice codec / mode - all the SIP protocols have gone pretty HD / zoom etc are HD at this point, a lot of cell has gone HD.

Are the bands really so crowded (think on 70cm?) that we can't afford the bandwidth for something a bit more HD?

Not sure about everywhere but here in Europe (Spain, Ireland) the bands are dead quiet. I became a ham in the 90s and every morning we had a call in on the way to work. Tens of people on the repeater. The repeaters are quiet now. The digital ones sound a bit more active but that's because they're relaying the whole country now.

Hf is still pretty busy I think but I don't do that. No space for antennas in the middle of the city.

But anyway there's definitely space on 70cm. The band plan would have to be redesigned though for wider channels. There's even more space on 13cm. Literally nobody uses that. There used to be some amateur TV but that's gone too.

And yes it's annoying that in this day and age digital radio still sounds way worse than ordinary FM at the same bandwidth.

DMR was designed for commercial land mobile radio.

It is designed to occupy similar bandwidth and have similar performance so that existing LMR spectrum planning assumptions continue to apply.

If you want HD audio, or better weak signal performance at the cost of audio quality etc, you need to design something different.

https://www.openresearch.institute/opv/