Re: So that's iOS 5.1 not just the iPad
"They can't win. Damned if they do, damned if they don't."
Pretty much. Necessity being the mother of invention - there is a very good understanding now how to jailbreak and root these days. To slow folks down, Apple would have to bring in a new team of developers(with new ways of doing things), and build a new bootloader and OS from scratch with no code re-usage to slow things down again. As has been mentioned before, if they had offered the ability to run unauthorized applications, then the necessity to jailbreak wouldn't exist. Once the Genie is out of the bottle though, its near impossible to squeeze him back in.
The other thing that gets forgotten, is that if someone has physical access to a device(phone, PC, server), you can't reliably secure it, at least not all of it. Like DVD's and BluRay. Both sides of the encryption are KNOWN, so there isn't any point. Same thing with bootloaders and such. Static keys means it will get hacked. The only thing you can secure is your own data with a random key (that you can't remember and have to write down on a postit note under the keyboard) and 256bit encryption or better. Although.. even that would get cracked eventually, especially if they turned over the keyboard. :)