The MC list is kept in the "registry," due to this it is impossible (to my knowledge) to "sync" it to the degree you're thinking about.
I believe this is one of those instances where you have to change your thinking to the way the software works. I hate the barriers as much as you do, but I have taught myself to keep the list a "Master" category list. In that I have a few "core" Master Categories and leave it at that and work within those limits. For me too many categories takes my way of thinking, away from the GTD style I'm trying to work with. It is a limitation in the way they programmed Outlook and while I think it is a huge oversite on the part of MS, it's not fixed yet and I have learned to live within the limitations.
When you think about it, the Master Category list (once setup) will work for a very long time before you need to add a category.
Just my thoughts,