I think one reason the early SS home version pins (Fireball, Evel Knievel, Alive!, etc.) aren’t considered as valuable as roughly-comparable pins from the same period is the lack of a coin door. Those pins just don’t look the same.
I really like the coin doors on all my EMs, even though they’re in my basement set up for free play. Otherwise, they just wouldn’t be as cool. If one of them had some plain door in front, I’d get a coin door for it.
To the OP’s point as specified in his edit, far as the mechs themselves, since no one sees them, I could do without them, as long as the outward look is there. But I think new pins should still have them so the operators have that option for earning.