A similar sentiment is on gizmodo. And when you look at the future windows platform i think you are right, Microsoft has to do it this way.
But in the short term microsoft almost has to start from scratch because of this reset. In the short term this will slow-down the growth of the ecosystem. High-end phone customers will wait for the WP8 devices, and developers will focus on the functions that are also in the low-end WP7 devices, since those are in use.
Microsoft is betting that the entire Windows 8 ecosystem will explode in size because of simultaneous phone, tablet and desktop launches. I fear all three will have extremely slow adoption because of the size of the change and hardware prices.
I also think that application development will remain very much separate for tablet, phone and desktop even with the shared metro interface.
But I could be wrong