Why does 4e treat death as a speedbump? Because WotC suspects that will appeal to their target audience, todays youth. And, they are probably right.
I know the 'it's a video game' mantra is seen as teh debil™, but think about it. Are there any video games anymore where you have only x number of chances and if you fail, that's it? Game Over. Start from the beginning again. I can't think of any off the top of my head. Absolute worst, in a CRPG you back up to your last save point and try again. MMOs, you simply respawn and try again. It's a fact of gaming culture, death just means you try harder next time, it rarely slows you down for any length of time.
So, that's why. D&D is, in fact becoming more like a video game in this and other respects. Is that a good thing? Remains to be seen. For the sake of the hobby and the trademark, I hope it is a gamble that pays off.