If sub prices would go up, there would be a direct correlation between the quality of the product and the content (expansion/patch). Good product = many subs, shit product = less subs. So if they wanted to cover their expenses from sub price only, they would have to make good patches. With store mounts, they are free to create whatever shit content, because whales and collectors will buy new mounts. so people who unlikely to unsub cover the "expense" of the people who do unsub.