I asked you to consider the question: "What can Apple to do make jailbreaking less attractive?" The answer should be obvious by now, so why hasn't Apple reacted? In that way, Apple encourages jailbreaking. Some blame is justified.
Ask yourself: What's in it for Apple? If you buy an iPhone with the intent of jailbreaking, Apple has made a sale. Convincing people to not jailbreak doesn't give much benefit to Apple. And frankly, your claim that Apple encourages jailbreaking is ridiculous: They do their hardest to prevent jailbreaking from happening.
But what Apple is really interested in is any improvement that makes more people buy an iPhone. And things that people jailbreak for are usually things that affect suitability of the iPhone for everyone, and would eventually reduce sales.