They were advised months ago that this could happen and they kept going with that. It might suck as a user, but you have to respect whichever standards the Linux kernel asks for.
a 100kloc hal shim for a single vendor is unacceptable. I don't blame them... If they'd presented this as a joint approach with nvidia and intel, maybe, but that is not the case... Why not make a HAL for Windows/osx and use a linux mode as the base?
In the end, it kind of sucks, but was the right thing to do.
I wonder how that proposal would go inside a corporation - "we need to rewrite our driver at huge development costs instead of further competing with nVidia because we need to make OS developers of marginal market importance happy".
One of the problems for AMD is that everybody uses nVidia for computing, and nobody uses AMD. One of the reasons is thaf they have been ignoring non-mainstream GPU market. Well, those non-mainstream markets become mainstream and if you fall behind it is almost impossible to catch up. I personally prefer AMD's GPUs for computing and prefer OpenCL to CUDA. But, they are minor, since nvidia has much better software offering. AMD absolutely need to offer superb Linux story if they want to get people to use their hardware for computing instead of nvidia. They need Linux more than Linux needs them.
AMD used to have much a much better hardware story for compute. I don't know how it looks now, but nVidia have absolutely stolen the market due, in part, to their excellent software -- even on Linux.
My only experience of compute on AMD was a FirePro v7900 -- an expensive, workstation-class card. With both the latest, and the 'workstation-class' Catalyst Linux drivers, my LuxMark tests came out very vast, but very red.
With nVidia, I can simply add a repo to my Ubuntu machine and have the latest stable drivers every time I do a dist-upgrade. If I want a solid, tested CUDA dev environment, I can install the CUDA repo and do likewise.
AMD have to make sure the end-user experience with these cards is as smooth as that, and that everything works.
I really hope AMDGPU-PRO is that experience. I haven't tried it yet, so I can't comment.
It's easy to dismiss enthusiasts / hobbyists / developers / gamers as a 'small market'. There was no 'pro gamer' market until ~10 years ago. Now there are entire companies built off the back of it. AMD cannot continue to leave a sour taste in end-users' mouths, otherwise there might not be any left soon.