Quoted from rollitover:overall antiquated gameplay.
Blasphemy! EMs have boatloads of strategy and modern gameplay mechanics. Royal Flush is one I like to use as an example. First, you gotta be a good shooter, to make the hands in poker to increase your end of ball bonus, but the value of the drops and kickout are increased by collecting jokers. Do you A: Maximize in-ball scoring by shooting for the jokers first then go for poker hands (tough 'n risky business), or do you maximize end-of-ball bonus by shooting the drops straightaway, easier, but less lucrative.
Wide open outlanes and tiny 2" flippers on the older offerings will chew up and spit out even the most seasoned players faster than BSD or IM could ever wish to do.
I think people who dislike EMs (or devalue them) simply aren't approaching them correctly.