Every now and then I see statements like this and it makes me cringe:
"Unless we are only documenting the As Is, business process modeling are made to optimize the business process, notably by using automation."
Aiming for automating processes might be a good strategic goal, but it will get you into a lot of both political and technological issues. How will information workers react to a project that aims at automating their jobs? What percentage of business processes can readily be automated with the available technology today?; think of the BPMN-BPEL chasm. Also read The Case Against BPEL: Why the Language is Less Important Than You Think.
In my opinion, you should do business process modeling with the objective to document the processes, enable visibility into the process performance for operational awareness (BAM, KPI, etc) and to achieve consistency and repeatability in the way the processes are performed - even by humans. Way too many processes that are core to your business (DDD core domain) depends on human interaction, and these processes are not going to be automated using BPM any time soon - however, they might get efficacious support from BPMS solutions.
The ultimate BPM automation system might be Agent Smith: "Never send a human to do a machine's job".