The majority of Radovan's concerns seem to be around the structure that BPEL enforces. Sometimes this is called a "structured process". These are processes where the actors are given rules and are told not to break the rules. Structured processes exist in every corporation that I've been in.
"Semi-structured processes" are those processes that have 'wiggle room'. That is, they enforce a base structure or flow, but at key points run-time decisions can be made.
"Unstructured processes" are really more about achieving goals via whatever means. Here, the participants, the activities and the order will all change at run-time in order to achieve the end goal. The down side is that this often borders on chaos and has limited repeatability - which is a key driver behind process.
What we are finding is that BPEL can handle virtually every case for 'structured' and 'semi-structured' process descriptions and execution. Unstructured processes usually don't lend themselves well to any kind of 'ordered activity machine'. Rather, these processes are more likely to be executed via 'process liberation' tools like Groove, where the focus is on communication and inter-team task visibility.
I don't fully understand the critiques of BPEL. It really is a powerful language - although I can see if you don't work in it where you might be confused. But... we have a team working on this all day, every day... as does Collaxa, FiveSight, SeeBeyond and a host of other companies.