As others has already pointed out, the goal of Falcon is to ease the creation of REST APIs and run with the best possible performance.
Usually, when you are coding a full API in Django or Flask you find yourself putting additional dependencies in, and this will impact performance and maintainability. Those dependencies won't help you get rid of the "opinion" or "initial purpose" of the frameworks: to build websites, and this will also impact maintainability and performance.
I'd like to know which aspects of Falcon's usability where found painful. I actually find it to be really friendly while coding, but I don't try to use it for stuff it's not designed for.
It'd be great to be able to post feedback to the UserVoice channel, or anything else, from a dialog in the devtools. That way devs wont forget their great idea while they finish their new neat feature.