It's less a resolution thing and more the quality of the optics. The Episode II and III cameras had really bad sensors and only 2/3" CCDs, just like news cameras--well, the prequel cameras were news cameras, retrofitted for movie use.
As the technology gets cheaper and easier to view, 3D and high framerate filming will eventually become standard, it's just a question of whether this is 5 years, 10 years, or 20 years. It's just a natural progression in the trajectory to capture real life. First we had sound, then we had colour, then we had 3D and now we have frame rates that better approximate real life motion. Doug Trumbull has been working on a 128FPS system for about 30 years, because after years of testing he felt that was the frame rate at which it would indistinguishable from real life. He held a screening once, a tech demo, and Spielberg was there, and the projection screen was inclosed in a box. Before the film starts a man walks out in front of the screen and starts explaining the technology and what they are about to see. Spielberg says something like "when is the actual screening going to start," when the enclosure surrounding the screen lifts and reveals the man is actually a projection. He was the demo, but he was impossible to tell from real life. I want to see that, I'm excited for that day, when films are in colour, in sound, in three optical dimensions, and in real-life motion.
We are on a trajectory for as complete an immersion as possible, and these seem to me to be pretty obvious routes. Some people have this knee-jerk "ah, it's a fad" mentality but I don't get that, it's seems more that people just don't like change, even when it increases the immersion of the film. Eventually they will accept it, just like all the people who thought sound was ruining films dealt with it. That, by the way, is true, there were huge amounts of people who felt that sound betrayed the very foundation of motion pictures, because it was a visual medium done in a certain style where people didn't speak. Same with colour, because black and white was seen as more artistic and proper--colour was a gimmick; and it sort of was. But ultimately it made the films more realistic, and that's what won the day.
The problem with high frame rate in the past was projection, and it still is today. But when we were dealing with film, you would have had to replace the entire projector. Now that we are in the age of digital projectors, it might be possible to just update or mod the existing hardware--I'm assuming that is what is happening with the Hobbit, it would be doubtful so many theaters would install new projectors just for one film. It's also easier to build cameras with higher frame rates now that we are digital, whereas in the past with 35mm cameras the entire thing had to be gutted from scratch.