Full disclosure: I'm a wire/gear head. I love mechanisms, and what can be done with them in the hands of someone with a true bit of 'clue'.
When you look at the levels of complexity that were achieved in the E.M. games, pins, bingos, arcades with nothing more than switches, relays, and steppers, it is hard not to be impressed.
If you can related to such things, then no additional explanation is really required.
Combine that with the art, the layouts, (from the simple to the totally bonkers) and the overall feel of the game, and you have something that is really hard to beat, even with the computer managed 'vegas' light shows being put in the games of today.
Each have their place, and either variety may not appeal to everyone... But there is room for all!
Are there 'bummer' E.M.s? Sure, just like there are bummer S.S/DMD/what have you games.
But find a decent one, that has been well looked after, and just enjoy the experience.