If you look at profitable companies in phone business (Apple, Samsung), they focus. They don't try to be jack of all trades. Sure, Samsung released an ATIV phone, but it never bother to update it or market it. The focus is Android and Galaxy product line.
For HTC, they try to be jack of all trades, there hardware is not as compelling and they don't have focus. The results are there to see.
Nokia chose a competing emerging platform with deep enough pockets to ride out the initial hiccups to root a platoform. Considering how deep rooted consumer alliances lies in the mobile world, and how it has been fashionable for some time to be owner of Iphone or Galaxy, i think Nokia did a fabulous job of atleast getting people to start noticing and talking about Lumia's. The numbers would start showing up as the platform matures. The shareholders want the results early and want it fast, which unfortunately would not happen in today's competitive marketplace. They would need to have patience. I for one am sure Elop is betting on the right things.
It's perfectly logical to focus on one platform after a while. This said i still think that Nokia, like other companies, should have tried both Android and WP platform and decide after which one it should focus on. Putting all your eggs in the same basket from the get go is rarely a good idea. It might works in the long run but i still think it was a bad decision (unless the infamous money hat was involved which would not surprise me at all).