A couple of points:
1) I think the "whale" model works well for ventures where you can charge extra for something that does not take much time and effort to produce. Using your example of kickstarters, it does not cost anything to list someone as a backer/producer/special friend in the credits, yet a handful of superfans will gladly pay $1000 bucks or more for the privilege. Similarly, video games can release "collector's edition" with extra in-game items, and maybe an early access period that costs the creator virtually nothing to produce, but can justify an extra $20 price tag.
By contrast, creating an RPG product requires 1) someone to write, edit, produce art, etc. for the product 2) physically producing the book, boxed set, etc. I am sure that WotC knows that they must sell X number of copies of a product to not lose money. With a niche field like RPGs if only the "whales" are going to buy a given product it will likely lose money.
2) Comparing D&D to Paizo is misleading because from what I understand Paizo currently has about five times the staff as WotC has for D&D. So don't expect WotC to be churning out two adventure paths and 2-3 splatbooks every year in the near future.
3) Selling a ton of splatbooks can make money in the short term, but it can also deter new players for picking up the hobby when they see there are dozens and dozens of rule books for the game. Even Paizo seems to recognize this with their new "core campaign." In past editions D&D has cranked out splatbooks as fast as they could sell, but this time around they seem to be taking a 'less is more' approach - sell a few books to a lot of customers, rather than trying to sell a lot of books to a few customers.
4) It is still very early in the 5E product cycle and I suspect Hasbro is taking a wait and see approach. If the next couple of product waves sell well, I would bet that they will ramp up their release schedule. If not I think we will see a minimalist release schedule and some sort of OGL.