No great product mind I've ever studied sacrificed making a great product for a more profitable, adequate product.
In the long run, the company that makes the best product always wins. Apple was never worried about cannibalizing the iPod to make a better product in the iPhone. You won't find anything in Amazon's leadership principles[0] that could justify this kind of thinking. Even Wal-Mart, after pressuring their suppliers for lower costs, doesn't keep the difference as profits. They push their prices lower and build trust with the customer.
Curing patients is absolutely a sustainable business model, and only the most small minded, short-sighted Wall Street suit would think it isn't.