The main idea is that there is a nice middle ground between pure SW, low touch SaaS apps and consulting services.
In particular this middle ground can actually help support a SaaS app until it reaches some level of critical mass. The early days of a PaSH app is about risk mitigation. A later stage company can use it to drive revenue up.
It's definitely not new, but it is a model I'm seeing more and more small team SaaS operators adopt.
Customers find it valuable because it ends up being a form of low cost, optimized outsourcing.