They clearly took many design cues from Zune, which was another excellent product I loved that did not take off.
I think if MS Phone had stuck it out a bit longer hybrid apps may have helped bring some developers in.
It sounds like Nadella still doesn’t get it though. MSFT tried several times to “reinvent the category of computing between PCs, tablets, and phones” and none succeeded. Windows 8 UC targeting tablets and native apps was a disaster and ate up a lot of goodwill. With tablet PCs and netbooks Microsoft had the right idea too early and with poor technical implementation.