Well these two were the creators of many of these big budget spectacular releases, especially back in the 70's and 80's. So it's their own fault.

I still think that there will be a market for indie films. It might mean more demand for art house cinemas.

I can think of any number of films in recent years with small/reasonable budgets that made it big, and across genres

The list is enormous. In fact with small budget pictures the stories are invariably better and by eliminating the need for special effects they can be much lower budget. Many actors love indie films because oscar wins are more likely. The big budget films mainly do better in the Oscar's technical awards.