Hubstacks may not be a prominent feature of competition freestyles any more but that doesn’t make them any less fun to have. Sometimes you just want to goof around and see what sort of silly things you can come up with. Sometimes you just want to “feel the gyroscopic power” as YYF puts it.
As for weight rings, some people just prefer the look of gold plating to anodized aluminium (I personally prefer anodized aluminium). Will it raise the price? Of course. Gold costs more and you can hardly expect the company to eat the cost. Is it just for the sake of raising prices? I don’t think so. If that was the goal, there are more cost efficient ways to artificially inflate the price like producing a numbered run, a limited edition laser engraving, or a limited run colourway.