3D printing is fantastic for terrain, which is typically larger and smoother, so it’s easier to hide or sand away any printing issue. It’s fine for things like busts or some display mini, where you can afford to be careful and spend the time fixing rough edges. But it really isn’t there compared to good quality plastic for smaller minis with dynamic poses. It’s too cumbersome, too finicky, and the material is too brittle or not hard enough. I don’t doubt that it will get there eventually, particularly for companies that can afford to invest in high-quality, expensive printers and material.

I think GW will sell in-store printed minis before sufficiently good 3d printers are common in players’ homes. The OP makes good points about why this is impractical in some ways, but I can see this happening for special releases or some less popular minis. The other side of the impulse-buy coin is that a lot of people need minis that are not usually in stock in stores. Then, waiting 15 minutes or even an hour (say, whilst you play a game or watch one, or paint some stuff, or just chat with fellow nerds) to get your mini printed beats the current "order on the website and then wait 2 weeks" process.