At the end of the day, ARM thrives because it's awesome in almost every respect over x86. Granted, that's a less-than-fully informed opinion, but if I recall correctly I've read some technical articles suggesting the instruction set was better on ARM for some reason or another; ARM being supperior power consumption-wise is well-known, and what ever happened to the rumblings of Windows planning on supporting ARM eventually?

I admit that sometimes I hate that certain manufacturers support x86 in a special way, such as Adobe providing a flash player only for x86 as a free download, but aside from the occasional proprietariness-limited crap, everything is doable on ARM really.