I haven't read your post, now I did.
++, interesting read, I mostly agree with many points of that
Still, I am not agree to waste plenty of resources just to accomplish some simple tasks. I do not want to get rid of car and use trucks just because I decided to pack my small boxes into huge containers.

Closer to your current point, there were no "6 major releases of Perl".
You probably meant some maintenance releases between 5.8.0 and 5.8.7?
Those are even not a minor releases, those are even less than that, those are maintenance, or patch releases (in my, probably broken, classification).

Did I tried threading recently? - yes, I did, in 5.8.6
As you already guessed, I failed, namely within Tk+Threads on Win32.
My attempt will probably fit into your classification of incorrect attempts, but, in my opinion, those were sane enough.

On the other side, I agree with an opinion that threads will mature faster if larger user base will be; and any support will stuck if all refuse trying.

add: sorry for my unperfect English. Some people say it is unperfect but perfectly adequate, I don't know :)
All I do know - I am unperfect :):):)