I kind of had an epiphany as to why Windows Phone isn't doing that well in East Asia.
You could point to marketing, entrenched products, all of the above etc - but after handling Asian Lumias set to Chinese and Japanese, and I started to think about a really big part of why it might put people over there off, even if subconsciously. Unfortunately I don't have screencaps to illustrate my point, but hopefully you can infer it from the info I've given - and feedback from real East Asian WP users would also be good to clarify stuff.
Now as we all know, Windows Phone is based essentially on functional typography as design element. The thing is, I saw that when you apply Windows Phone design practices to East Asian character sets, it's no longer minimalist, but barren.
If you take Japanese as an example (which exhibits this problem particularly badly due to the form of the characters), they have three core character sets - two of which are mixed in everyday Japanese (the Chinese-derived complex characters and a simpler character set) and a further, slightly more simplified (in terms of shape) character set which is used to denote onomatopoeia and Western words phonetically. All of these characters are written in the same space as two ASCII characters. Asian Windows Phones use the same font size to represent elements as Western character-set-based phones, and character spacing is also fixed, which also IMO has the side effect of talking away a lot of the elegance of Windows Phone typography-as-design-element.
So for example, what you find in the XBox Music app for example is instead of
on the masthead to start with - which onscreen looks good and in keeping with the character of WP, there's
"ミュ-" (which is a phonetic-character-set representation of 'mu')
Again I don't have a screenshot, but I believe it doesn't take a Mac-stroking typography masturbator to figure out that looks horrendous on the screen when scaled up to the size of the western language fonts.
Skipping across to Chinese but sticking to the XBox Music app, let's go to the categories. All the entries there - music, videos, etc - can be written in two Chinese characters (e.g. 音樂 = music), and they go down the screen instead of across, with the font size again being the same as the Western equivalents. So what you have there are 8 characters uncomfortably hanging slightly above the middle of the screen with nothing else - which is again enough to turn minimalist into barren. There are elements of this 'lost in translation' all over the OS.
The second problem is that the Asian fonts in use on the Windows Phone look ugly themselves when scaled up - blocky is the best way to put it, and it only serves to highlight the barrenness.
The upshot is that where the OS is dominated by displaced-Western-idea-of-typography and not iconography, it looks terrible (to a non-East-Asian eye, at least). I don't know what to suggest for a fix, or even if Asian design people look at it in the same way - but there's no doubt to me that something is definitely off when you transpose the Windows Phone UI to East Asian languages.
Just in terms of how things look, the fixed-space icon approach in e.g. iOS seems to look a lot better across the board, and that Windows Phone appears to fail to deliver on one of it's key aesthetic premises in these languages. I'm starting to think this might be a big deal for 'higher-end' users in these markets.
East Asians - am I talking out of my butt here?