Presumably, cave painters painted paintings for others to look at for some reason or another, and could be considered bad at their craft if others felt they had failed in some purpose, whatever that was.
In many cases we can only speculate why ancient artists created the rock and cave art that they did. The cultural meanings and reasons are lost to us.
Does that mean we can't admire their beauty? That their destruction would not, or should not, matter to us?
Something that is poor quality is something that isn't very good at doing whatever it is that it's supposed to do, and in the case of consumer products, it's to be used by the consumer for some purpose. So, who's the judge of whether or not a consumer product actually does what it's supposed to? If it's not the consumer, who is it?
A high quality computer display from 1987 isn't much today.
When we're talking about the quality of a film, or a piece of rock art, or a novel, or a RPG, are we making an assessment of the utility of a consumer product?
Is utility the only metric for judging human creations?
This is not how I approach film, or literature, or RPGing. I'm not looking for something
useful. Typically I'm looking for something that is
moving - that evokes unexpected responses in me.
(Upthread I mentioned my tendency towards sentimentality. One way to think of sentimentality is as the creative coward's response to the threat of a truly unexpected response.)