I took a swipe at Bruce Silver a few days ago and implied he didn't know anything about WebSphere Process Server. Somewhat embarrassingly, it turns out that he has written a 28 page report on it and that it appears as the first link on the Integration Developer documentation homepage. Oops...... Sorry, Bruce. (Given that he also hints at the existence of such an article in the post I referenced, I think an apology is the least I owe him).
When a new specification is proposed - especially a revision to an existing one - it is incumbent upon the proposer to justify the need it. I think the various "Human Task" use cases that Bruce outlines are pretty important but it's easy to see how this could be construed as an attempt to make it harder for other vendors to conform to the spec.
My view is that the problem is actually the other way round: I'm increasingly of the opinion that standardisation often occurs too soon and that major revisions are a reflection that the initial specs fail to anticipate potential problems or extended use cases. Unfortunately, if vendors choose to delay standardisation, they're accused of being proprietary or risk finding themselves with no influence amongst those who decide to standardise earlier. When the incentives are so strongly stacked in favour of early standardisation, it's not surprising that those who gain the most experience with a spec discover its deficiencies and seek to remedy them.
What I suspect has raised suspicions around BPEL in particular is that there have been plenty of attempts to describe business processes in the past... this is hardly a brand new field (FDL, FDML, BPML, etc, etc).... I don't have a good come-back to that yet. I'm working on it :-)