The reason the IAU doesn't want to tackle extrasolar planets is pretty simple: while we know they exist, and have even imaged a small number of them directly, we really don't know that much about them. Is what we detect typical of the population, or is it an artifact of our detection methods? Do they have moons? Since we can't even pin down their characteristics yet, it doesn't make sense to attempt to make up standards for classifying them yet either. Yet. I'm pretty sure that at the very least, the planet/moon distinction will be carried over to other systems.
The ancients did not know about Uranus (as far as we know, it may have been detected and later forgotten) because it's not visible all the time, making it hard to track without photography. But it is naked-eye visible some of the time. It's also frigging huge, enough so that the orbital dances of Uranus and Neptune have had massive effects on the evolution of the entire system. Any definition of planet that excludes the two ice giants is willfully ignoring their significance. If it turns out there is another Earth-mass object out there substantially directing the evolution of the Sednoids, it would indeed be fair to argue that it too is a planet. It is busy clearing its neighborhood, however slowly.
As for lumping the terrestrial planets and the gas/ice giants under one name, you have a point. If the IAU demanded that they have two different (but short and easily spoken) names, I'd be happy to go with that.