As former rep for a PSIM market leader, I say with conviction most PSIM systems are over-sold and therefore rarely meet client expectations ... and they do not usually implement easily (countering the "out of the box" pitch delivered throughout the sales process).
I used to say that PSIM is a great story with an ending that begs a sequel.
That said, if all of this is explained to the buyer in advance of money changing hands, PSIM creates a much more usable operator environment for large, complex end-users who have a variety of security technology spread across their enterprise. These types of end-users don't have many good choices. They can:
1) live with "stove pipes" in their command centers/ SOCs -- high risk and terribly inefficient.
2) count on manufacturers to work together to create a more operator friendly, open-ended, viewing platform - hahahahaha... funny.
3) invest in PSIM - expensive and often dissappointing.
What else is there? Open to ideas.