Because the HTC 8X was a damn beautiful device - it out Nokia'd Nokia. The limitations are what did it in - 8 or 16gb storage w NO sdCard, the camera was subpar. I bought the Lumia 920, because of the 32gb onboard & coming from a Nokia Symbian device (N8) the camera.
Removal battery - hmmmm, the reason there are non-removable batteries is, they can cram more power / capacity into the same space (and to a lesser extent, it's prolly cheaper). Think about that when you complain of a non-removable battery.
I currently own the Lumia 1520 because it was the best device for my needs. My wife needed to replace her iPhone & liked my phone better. Thought about buying another Lumia 920, for her, but gave her mine & got the Lumia 1520. It's BIG, for about a week, then everything else is small. Fits in my pocket (front or back), the 6" screen is a viewing delight. The camera, sdCard slot & processor (GPU) are plusses. Minuses include the lack of QI charging (AT&T model) and to a minor extent, it's big.
For the future, the HTC W8, LG Uni8 or the upcoming Samsung WinPhone flagship may eclipse the Lumia (MSFT) line...
For NOW, my Lumia 1520 should cover me for the next 12 - 18 months (prolly right up to WinPhone 9). I do currently luv my phablet..