I'm currently selling a pixel-art drawing program called Cobalt, which is built on Bedrock (you can see a demo of it running at the bottom of the project page). It was initially only available for Windows and Linux, but I wanted to make it available for the Nintendo DS as well, so I wrote a new emulator and now it and all of my other programs work on the DS. It was far easier to write the emulator than it would have been to figure out how to port Cobalt to the DS directly, and now I don't have the issue of having to maintain two versions of the same software.

It's true that 64KB is pretty small in modern terms, but it feels massive when you're writing programs for Bedrock, and the interfaces exposed by Bedrock for accessing files and drawing to the screen and the likes make for very compact programs.