Thats a really nice rounded SS collection. I personally LOVE Farfalla. It was a well designed machine, and it played a little like a late Bally SS. I repaired one late last year and I enjoyed playing it once finished.
The simplicity of SS and EMs is also highlighted in competitions. They are nearly always all DMDs. I think because serious players play "serious" pinballs, which i think are DMDs. You walk away from a Sky Jump with 50,000 points and that's a good game. Just plunging first ball in a DMD will earn you 50,000.
When I see a line up of DMDs, I'm not as inclined to play them as I'm not all that good at playing them. When I see a line up of SS as in the pictures above, my first thought is "which one do i play first" ? That is because I grew up on these games, and they bring back a heap of memories. So age has a lot to do with it. If the younger kids like the DMDs better, it should be encouraged, because I've found younger collectors have small, but late model DMDs and older guys have sheds of older games.