I can see where you're coming from. You look at Arch, or you look at Sid, and you say "wow, look at the recent versions of their packages. Ubuntu should have these as well".
But this is not the way to go. Ubuntu has a very clear goal: to bring Linux to the mainstream desktop. This goal means taking some decisions, such as shipping with binary drivers, fitting the distribution on one CD, and keeping a reasonable level of stability. The 6-month release schedule is a key ingredient in the tradeoff between novelty and stability. Those who want bleeding edge should turn to another distribution, not try to change Ubuntu.
OK, so what about a rolling release version as a complement to the stable releases? I don't really mind that, but I fail to see the point. User who are advanced enough to understand what "rolling release" means should no doubt be able to install Sid.