I would gladly accept a void warranty if I wanted to overclock but I'm sorry I don't find losing the warranty acceptable because I wanted to install mt-toggles, or mobile hotspot.

Of course there should be a balance between security and freedom, (see here) but a switch like the one on the N9 and Android (allow installations from external sources) is enough. Also, although a rootkit is a serious threat we're not running a server in our pockets, and a random app without root privileges is just as harmful. An evil app doesn't need root to send my pivate data to the cloud, doesn't need root to send billable sms to premium numbers, doesn't need root to spam my contacts with ads, wipe my data, record my conversations, broadcast my position, take photos of me in the toilet.

So for me a locked kernel is just a lame excuse for security where there is none. Just make the cpu non-overclockable, or trip a one way switch to void warranty when overclocked. Even that could be contained (allow other components repair even if cpu is overclocked), but I know I'm asking too much.