If it is so obvious, and such a great business model, you should start a consulting firm and make millions advising pretty much 100% of the MMO market.
Is there even a single major title that works like you claim should be a no-brainer for the industry? Not one that I've played.
Every MMO before WoW was group-oriented. That was when the industry was thriving and exploding in popularity. Now it's contracting and dying, with most new releases fairing anywhere from fair to terrible.
The facts speak for themself. The industry can't sell subscriptions anymore for the games they are making. If the product is so good, and this is what people want, why can't they attract anywhere close to the numbers EQ had 15 years ago, even when giving it away for free?