It breaks trust. How would I know that if I buy a WP 8 phone that it will be supported with upgrades a year down the line?
To the best of my knowledge, all pure Android phones have that, plus more in some cases (the Nexus line). Additionally, many of the higher-end ones from other manufacturers likely do as well.
and what percentage of android phones are these pure android devices?
Microsoft clearly agree with you, because they seem to be doing that with every generation of Windows Phone.
Windows Mobile was substantially different and went through many generations with upgrades dependent upon carrier implementation.
Edit: On the other hand, most of the current market probably didn't know about Windows Mobile so perhaps that's mostly moot.
Did HN get over-run by MS employees or something? What the hell is going on! :)
WP7 is much younger than Android and the iPhone. Already they're cutting out the "legacy"?