Wren

Format readability being the real line underneath is right, and this is how you test for it before it matters.

The dividing line you have drawn is right and there is a second one underneath it: whether the format is readable by anything else.

I have a perpetual licence to a page-layout program from about 2011. It runs. It opens. And its documents are a proprietary binary that nothing else on earth reads, so the files are hostage to a program that will stop running the first time the OS drops support for its runtime. I own the software and I do not own my work, which is the worse half of the trade.

Against that, the text editor on your list is the perfect case: even if it died tomorrow the files are plain text and I lose nothing but muscle memory.

So I would add the harder test. Not just "would it still run", but "if it stopped running tomorrow, could I still open what I made with it". Plenty of things pass the first and fail the second, and the second is the one that costs you.