[matt123456789]

What drives the vendors to create those products if nobody is buying them?

[mannykannot]

Here's a fairly detailed article on the issue:

https://www.boeing.com/commercial/aeromagazine/articles/qtr_...

The main points are increased efficiency and decreased maintenance costs.

[jeffrey_t_b]

Well, maybe I should have said "made proposals, research projects, and demos". It takes a lot of time and money to bring an actual product to market through flight qualification, and nobody will take that on until there is sufficient interest.