http://www.polygon.com/2014/9/23/683...released-games
Crixa. Warcraft Adventures. Starcraft Ghost. These were all games that were pretty far into their development before being cut. Let's not forget Titan either, which spanned years to develop. What about Diablo 3's alpha development prior to 2011? You can still find some of those images online somewhere, the prototypes for their D2-esque sequel that ended up being scrapped completely.
I understand that from your perspective, a company that spends money developing projects that go nowhere is a good way to go bankrupt. But you haven't followed game development of Blizzard closely enough if you say this, because if you did you would realize EVERY one of their games has gone through shit-tons of iterations and risks to get to where they are now.
Diablo could have been a turn-based RPG if not for the lead programmer's change of heart to go Real Time. Starcraft was initially born as a Warcraft 2 sequel in space, full of bright colors and cartoony sprites. Warcraft 3 was originally designed to be more of a third-person RPG than an RTS. All of these are built on trial and error. Every company goes through this process. The best games are built out of iteration and a heavy dose of polish - even if every company doesn't have the luxury of time and money to do it as well as Blizzard. I'm not sure if you're in the mindset that Blizzard doesn't put money into things that will eventually fail, but that's really the nature of the entire games industry. It's built on risks and potential to fail. Companies literally take massive loans to create a product, which only makes its money back on release IF the product sells. If they don't, companies go bankrupt. Blizzard is not immune to failure, but they are structured in a solid position based on their previous success. They have the flexibility to experiment and take risks. But these risks are focused on reaching out to new players, finding more potential growth and expanding their future prospects. Vanilla is a risk that does none of these, and that's why they're so hesitant to pursue this venture.