It's about efficiency. Any business is about efficiency. Nobody needs business, that gets paid for doing nothing. Yeah, it's so nice to charge sub fee for listening music instead of selling it. Cuz you can make one track and earn money forever. Yeah, people die and new ones are expected to buy everything from scratch. Well, not everything. That's why it doesn't always work. But at the end we want to pay for product. That's why it's bad, when companies try to turn their products into services to switch to sub fee model, when it isn't justified. It means, that they're ineffective. They have offices, they have to pay rent for, they have employees, they need to pay to, they have investors, who want their dividends, but they don't produce anything useful. They just exist. Hence it's called "existence tax".
I know, that they expected RMAH to become their source of infinite "sub fee" and it failed. But their expectations were set way too high. They saw D2's item black market and wanted to control it. They could release D3 as purely SP game and switch to B2P model, but it just wouldn't have been so super-profitable, as sub fee. They just didn't want "small" money. They wanted big money. Blizzard are well known as ineffective company, that gets super-profits while barely releasing any new games. Do you think, it's good?