If you want a wired controller, just buy an extra long USB cable from monoprice for cheap. It's been confirmed that the PS3 controllers will send their information over the cable instead of wireless when plugged in.
Rumble can actually add a lot to games, especially in the area of immediate tactile feedback. What's easier to interpret when you get hit, some vague red flash on screen, or the controller shaking. The controller shake is much more easily recognized becsause it's a tactile sensation. In games, your visual processing is dedicated to things like finding the enemy, aiming, etc... In heated battles, it can be difficult to switch your focus from the fight to interpreting red flashes on screen to see where you've been hit from.
But that's just one use, there's a lot more cooler uses, or simpler uses that directly help gameplay. But namely rumble can be used to replace an on screen indicator that would otherwise crowd the screen, and does this in a way that engages your sense of touch, leaving your other senses able to focus on the game.
This is why I was hoping Sony went ahead and licensed Immersion's TouchSense technology for the DualShock3. The description and actual hands on comments sounded very cool. The system was powerful enough to do some very subtle vibrations, low level hums that could simulate holding powerful objects like a lightsaber or magic sword. It could also handle more localized rumbles, you'll feel the rumbles pushing in a certain direction to more easily find where you're being shot at from.
The technology is starting to be put into other devices like phones and other hand held devices, the tiny subtle vibrations it gives help users know when they've done something. Kind of like how the Wii remote vibrates ever so slightly when you point the curser over a button. Imagine in a game where the controller gave you a subtle vibration when you pointed to an object of interest, maybe a hidden wall, or something. While it's not a whiz bang amazing effect, if used properly rumble technology can add a lot to games.
Alas, it doesn't look like Sony went for the TouchSense technology, I think they needed to cut costs, or it could have something to do with MS' lawsuit against Immersion where MS made a deal with Immersion that they wouldn't license their tech to Sony.