There is only one reason that the situation is so good for running bleeding edge inkscape on windows. Somebody wanted it, or thought it was needed. So they sat down and did it. 1000s of people benefit from this work. It has dramaticly lowered the level of expertise needed to build inkscape on windows. Bob and whoever else took part in this work, YOU ROCK! Thanks.
Linux is a different world. In general users are more tech savvy (because historicly they have had to be). It is pretty normal for a user to compile software. Most often the dependancies are installed or in package repositories, so things don't ship with it.
Worst case scenario someone could make an Inkscape live CD. But 6 months really isn't too long to wait for a distro supported package for someone who doesn't want to compile it.
I guess that is the reason distros don't have packages newer than 6 months. They have to support the software they ship. If they were to constantly update to the newest packages, their distros would be to unstable to support. (unstable meaning changes fast, not crashes often.)
Aaron Spike