It's just good news when you can find source code at all instead of just being told vague things about something the author did.
Absolutely correct, and not in a good way
Though to be fair, people doing research have other interests besides maintainable code (though half or more of the annoyances will probably come and bite them later)
This is extremely common, and I don't see why it should be allowed. I could easily write a paper claiming some kind of interesting result, fake a few "ground truth vs my algorithm" pairs, and talk a bit of mathy-sounding piffle about what it does - and it would be indistinguishable from many papers I have read.
In my opinion - provide runnable source, or what you have isn't a paper, it's a boast.