First of all, you're welcome. No, seriously, your appreciation for how many thousands of hours of work have been poured into Git for Windows to make it what it is today is very heart-warming. The fact that you dedicate a couple of seconds of your life together with your impressive command of the English language to express your gratitude reflects favorably on you.

The fact that git-svn is supported on Windows at all is the result of multiple months of hard work of a few very dedicated developers you might just as well be grateful for. If more people would have kept that in mind, and offered gratitude instead of whining, it is possible the principal developer behind that effort would still be interested to work on it.

Now to the technical reason why Subversion support was not upgraded in a long time: It is really tricky to build. git-svn is actually a Perl program, so it uses the Perl shipped with MSys (see this question for details). As git-svn is a Perl program, the Subversion binding used by git-svn is actually a Perl extension. It is not trivial to compile that extension on Windows (due to its lack of POSIX support and due to the lack of so many tools Unix developers take for granted), and so far nobody has successfully completed a Subversion upgrade.

So: what is the solution? Ideally, someone who needs it badly enough to tackle the upgrade of Subversion, contributing the work back to the msysGit project. This is Open Source, after all, therefore everybody is welcome to work on it. You could even offer money for somebody else to do it for you. One thing is almost certainly not going to work, however: complaining and trying to bully volunteers who do not need Subversion integration to fix your problem; that only will accomplish only two things: to make you look bad, and to make sure that our loss of interested developers is permanent.