It was obvious when the new Substance 3D tools were announced that legacy functionality would be ignored completely.

This is frustrating to us who are trying to use what Adobe itself refers to as "Vector Graphics Software" to create vector graphics. It certainly is very representative of what modern Adobe prioritizes and how haphazardly it implements and then abandons things to rot.

I have the feeling that there are a lot of new features introduced that are not properly finished/polished.

If they ever close the gap — yes.
At the moment proper vectors are not just gap, but a canyon. And I can’t say they are in a rush to close it.
Besides that: no revolve direction control (they are just opposite compared to classic), no fit mapping or decal snapping, no partial presets, no lighting lock... the list is long. They accomplished a lot, but I feel it slowed down recently.

I remember this conversation with a high Adobe employee about the gap between classic and the new 3D:
Ultimately we don't want there to be things that only classic can do. These are super important for us to see as we work to close the gap.
It's such a better and more modern foundation - there is a lot of potential upside here. And it will be a superset of what Classic can do.

Classic 3D hasn’t changed... that’s the problem. It does not not get changed and probably won’t be changed. So instead of trying to fix it, the team seemingly decided to leave it as is and try anew.
So either you are correct with 'something else broke it', or it’s a general notion of 'software becomes worse'. Hard to tell without an actual file you’re struggling with.
Having vector 3D, REAL one, wit ho no raster-trace-over is definitely a thing many users want... they don’t vote though! Soo....

I used classic but that has not helped me produce a clean, easy to use vector. I used Ray tracing but it only created outlines that I cannot easily select and some of the shapes are completely missing. I know this capability existed b/c I’ve used it in the past! No idea what’s changed but it feels like Adobe developers are constantly “fixing” things that aren’t broken… leading to functionality that is broken.

Yes, we need the ability to convert 3D to simple vector art to revise colors and edit as needed! Please add this functionality. I do not see a vector output option. When I try to use "Ray Tracing" the output is too complicated. When converting type to 3D, I need simple access to change the depth portion as a single color and the face portion as a single color so I'm not stuck the with difused output color change.

Thank you for the information, Egor! That's good news.

I use 3D-vectors ALL THE TIME. 3D vectors work seamlessly with vector illustration work, and are vital for good workflow.

3D-raster/bitmap is almost useless. There are countless applications that do that already.
PLEASE PLEASE PLEASE do not abandon 3D-vectors!

Thanks for there concern, Mark! Proper vector expanding is in plans for next builds. It should be better than the current implementation, which you can try in the 3D & Materials panel's menu, by toggling the vector output option.
Not a convenient way, I know.