> Exactly. Rumble is kinda critical to the experience, at least for me. It's just how I > played back in the day - plus there are certain games that require or rely heavily > upon it to work properly such as Metal Gear Solid. I know not everyone feels this > way, but games without rumble are really missing a dimension. I'm using Mednafen and > not MAME primarily for this reason.
In my experience when I realized I really missed force feedback was when emulating Final Fantasy VIII. Using a GF like Sheeva didn't feel the same. Force Feedback just like that VMU small screen on the Dreamcast can be crucial for some games either for game mechanics or pure nostalgia. The same could be said about linking two systems together or supporting weird peripherals.
I dream for the day MAME could consider an smartphone as an input controller, so you could make use of the camera, microphone, touch screen and tilt sensors for systems that need them. But that's something too far away to consider for now.