They priced the 950/950XL same as iPhone and Android flagship phones. Yes, I do understand the 950 and 950 XL have flagship hardware, however, you do not priced it as your phone is in high demand.
If they priced the phones at 300, it would sell a lot more. Developers do not want to develop for an OS with no users.
Not only the hardware price was bad. The fees to developer was also bad. If I recalled correctly, they also want to takes the same amount of fee as Apple and Google. If I was Microsoft, I would not charge developer any fees for 3 years just to get them on board.