Most companies would sue, create anti-hack software updates, etc... if they were serious about eliminating jailbreaks.
Apple has done nothing about this, petty little software updates, but they've left the infrastructure wide open since day one. They could have closed/ended this with the 2nd revision of the iPhone but they didn't.
They didn't because this is Apple's alternative to Google's "beta forever" program. They've learned a ton of what people want, (think gigantic user testing group) what people are doing with their phones and what they want.
Microsoft's legacy support has made them what they are today, to some extent. However, it's also what's put them behind a major sized 8-ball as well. If MS were to lose dominance in the desktop market, legacy would be cited as the #1 reason why. It's held Windows back for years, stifling any innovation they buy or steal.



