It really frustrates me that authors are not responsible for compiling and distributing their software, only then will we have software upgraded regularly and quickly.
Isn't creating one of those Windows installers also complicated? To me, it seems even more complicated than packaging software for Linux, yet it has never stopped anyone.
which distribution should they compile and distribute (sigh) for? Not to mention basic problems like "should I integrate with GNOME, Unity, KDE or nothing at all?"
There are only 2 popular package formats: deb and rpm.
I don't have any experience with RPM, but to build a package for a reasonably big part of the Debian-based world, you have to set up a build system (pbuilder/cowbuilder) and tell it something like `for DIST in lenny squeeze wheezy sid lucid maverick natty oneiric pangolin do; git-buildpackage ...; done`
The problem is, to get it right one has to find and read TONS of documentation.
I don't think the Gnome/Unity/KDE split is nearly as significant as people find it. You don't have to support them all! I use KDE, and programs written for Gnome fit right in. As far as I know, there is no reason at all to depend on some particular environment exclusively; even things like notifications work uniformly across different systems.
Why not all of them? OBS makes this easy. Big projects can run their own OBS, and for us others there is the public instance provided by OpenSuse. Builds many versions of all major distros.