There are a lot of specialized tools now that some fail to see other "potential uses" for such tool.
I used it (using a diamond lapidary bit) to sharpen my bandsaw blades and more than paid for itself in just a few of those. I also use it to carve wood using burr bits. Like you, I've used it to polish old folding knives using the felt buffing pads and some jewelers rouge. For heavier application, I have a buffing wheel mounted on my bench grinder/sharpener as well.
My wife & I used to carve gourd and I needed a really small cutter (so I can make tight turns) and I can't find one so I made my own bit out of aluminum soda can mounted on a mandrel. It worked very well. I didn't really need it to be very sharp since the gourd is soft enough and the speed takes care of it.