Have EULAs been upheld in court? The idea that I need special permission to use software that I've purchased seems a bit ridiculous. Kind of like a EULA on a car that restricts my driving to Ford toll roads.
You are correct that consumer EULAs haven't really been tested in court, but that is irrelevant to this discussion. This isn't about the EULA. Apple is not stopping you from putting a third party app store on the device. They are stopping you from putting a third party app store on the stock iOS. If you jailbreak, then you can put Cydia on it.