Then why did MS developed their own platform. Should just have developed apps for Android and Iphone because thats what works and what people like. They would have probably made more money this way.
They got into the game late so it takes them a bit. I think WP8 was just to get their foot in the door and WP8.1 is the real deal. Can you imagine if WP8 never came out and it was only WP7 waiting to update to WP8.1. If this happened they would be super behind because a lot of apps were possible due to WP8.
In the short term they might have made more, but its not very stable when you don't have your own eco system, because android works better with google docs not office because google owns android.
And wp8 is not by definition a placeholder to get their foot in the door, just look at the early iOS and android versions.
You learn alot from feedback and updating regularly is accustomed in the mobile world.
In that sense ios 6 was a placeholder for 7, because 7 brought the "bang" and 6 was just a refurbished ios 5