Adobe engineers can't be that bad, so this obviously is a management issue. They just don't care of Linux. On the other hand, it looks normal to devote more time to Windows and MacOS X versions.
There must be also lower management issues. Their Flash player sucks for video in all platform, and I agree, the actual engineers can't be that bad. But even if you have great minds, this can go to waste in a corporate environment if you make them report to incapable people.
Case in hand, a sensible low-level manager would have spent some resources, as you say, maybe a week work, not only to use or hack around the existing api's, but maybe just propose a wrapper to unify them (as opposed to bitching in a blog). I know part of this may be easier with Gallium, but they have a need today and they could have contributed to a solution. They have the (wo)man power. And it is in their best interest.
I think disregarding Linux is a HUGE mistake, not because of the desktop market, but because of the netbook/umpc/smart phone/tablet market, the appliance type market. Linux is huge there. And you want people to use your freakin' flash in all those. Oh well!
I would be more happy if they could focus on pushing stable 10.0.x 64bit version. Current alpha works, but it crashes and freezes quite often.
FWIW, and this could be a coincidence, in my ATI system it crashes a lot (freezing the computer) in Ubuntu Karmic with Catalyst, and it runs "fine" in Lucid with the open source stack.By "fine" I mean it doesn't crash, and performance is as good as it gets in flash.