I am not sure if and how many Stern has sold, but I completely understand the market behind this.
For upper middle class and rich folks that have personal game rooms, they want some sort of pinball to go with their pool table, slot machine, dart board, etc. When they get the idea of owning a pinball machine they visit the closest dealer and see T2 for 3800, a T3 for 4800 or some old 70s game for 1500. To someone who knows nothing about pinball, this is brand new, easier to manage (physically) and has alot of what they see in T2 and T3.
Personally, I like the idea, but I don't like the execution of it as it just has a "kids toy" look to it.