for the end user, potentially niche, yes. I would argue it allows for anyone to hack around with the file which is a positive in my book

for development though, I'd say it's quite useful. I work in a 3D editor and having data in a binary blob is a pain as you need to use your custom serialiser if you want to inspect the data. If a file is corrupted, good luck figuring out what was there, what happened, etc