I have very mixed feelings about this very topic. As a developer, I completely agree with you. Hardware should be hackable and software replaceable.
But there's also another side: computing has become a lot easier for the average user. E.g. the iPhone and the iPad were the first computers that my mother really grasped and was able to use comfortably on her own. The limited walled garden approach to computing ensures that she doesn't accidentally install malware, etc. In the end, I think the secure, walled gardens are useful to the average user.
Of course, the inherent danger is unfair competition - the gatekeeper can decide to reject software whenever it wants and impose fees and crazy rules. Since in EU, we are not completely adverse to government intervention, I think it is best that the European union would regulate such walled gardens, e.g. by limiting the percentage that the gatekeeper can charge, by requiring that the gatekeeper accepts all software that is not malicious, and requiring that a method should be required to unlock hardware. I that putting think such regulations into place will be much more effective than fighting windmills.