I am constantly amazed or at leat I used to be that software vendors
cannot supply a decent removal tool that completely uninstalls their
product. I mean, what's so hard about removing everything since they
decided where to put it in the first place.

Because it takes time to write code that does that, and their managers don't
want them to take the time to do it. Who cares if the registry get bloated?
I maintain software that is buggy as hell. It remains full of known bugs
because managers don't want to bother fixing bugs that don't pop up very
often. It's not the fault of the coders (for the most part). It's the bosses
that say don't fix this, don't do that. It costs money to fix it, and it's
not worth fixing.