Okay, party pooper time: RERAIL
Just a FYI: When I wrote my answer I noticed that I was late for work, so I had to wrap that one up quickly.
As for your post (and I resisted to quote it ;-)):
In regard of PR you are a bit contradicting yourself. I'm willing to believe that Valve employees actively communicated with individual players (had some of those myself), but outside mailing lists there was almost no communications with (or even towards) the community at all. You had the occasional post in some more popular forums. That was pretty much it.
Back in those days we always joked how terrible Valve was on the PR side.
Compared to that I see improvement today, though of course things could always be better.
As for them making errors in the past or outright handling things wrong:
Many of those I can't comment on without knowing more facts. However, I have no intention to canonize Valve. They will probably have their skeletons in the closet. But that's a different discussion.
As for your comments on steam pricing: You could be right, but apparently Steam is very successful (just a few weeks ago the german computer magazine c't wrote a bit about steam, and as a selling platform it apparently is doing quite well).
As for your many comments on class balance:
This again is a different discussion. Many of those do not qualify as bugs, those are class tweakings on several levels and a redefining of the classes which is in the flow. Some of my thoughts about that you can find
here.
I agree with demos, but that's a global problem and probably caused by game engines becoming so huge that demos might no longer be feasible, even with today's huge storage capabilities and broadband connections. But yes, it would be nice if demos would be offered more often.
Coming back to the issue at hand:
When I asked you to specify the mentioned drop in quality I was under the impression you were referring to the technical qualities of Valve, not their overall attitude. I still don't see that they screw up more than in the past. Nor do I think they screw up more than others, most definitely considering the frequency and extent of their updates.
Still owe you an answer on playtesting:
Yes, if they'd played the final release they should have noticed the bug (unless the environment in which they run the game is different, but that would disqualify it for playtesting). So chances are that they either didn't playtest it thoroughly or that the bug was introduced very late in the game (I'd like to think it was the latter). So yes, they screwed up.
However, I'm sure when you look around you will see a lot of applications - commercial, private, even open source - which had bugs slip through, sometimes equally obvious ones. Such things happen. It's not good and nothing to be proud of, but in a busy working environment, perhaps even under time pressure, things slip through and test are not done as thoroughly as they should.
And for that reason nobody should sit on a high horse and accuse Valve of sloppy work and worse unless he can point to a 100% error free track record.
Also I take comfort in the thought that last monday morning probably wasn't the most comfortable time to be a Valve employee

.