As others have pointed out, at least they should allow third-parties in where users could let trusted parties (from his point of view) provide him software for a machine he owns.
People are being näive thinking this is really about security, when in fact, its about control, power and profits. And when (some) people wake up to this fact, it will probably be too late to take any action. And i bet the majority wont even know what they have lost.
Its clear they are not thinking in their users insterests first with this move, because they are giving security with one hand, and taking freedom with the other hand.
For instance, if some app compete with them in things they think is strategic, with the control they have, they can make the app vanish and not be a problem at all for them.
We see this happening with Google everyday in search results for instance. We saw this with Windows before, but this time i think it will be much worse..
Hackers will find a way to unlock the kernel, but im sure by that time, those companies would be so powerful, they would have a legislation for that, so those kind of actions could be punished with fines or even prison.
I know im exagerating in this last scenario, but it is all possible, and with time it get more and more likely to happen.