As others have said, virtualizing x86 to the cloud isn't the best option for everyone.
Why would anyone rather have x86 vs ARM? Compatibility. All of your existing x86 games and applications can run on any device. Plus, the power efficiency of x86 is (arguably, obviously) on par with ARM finally. Even if you don't believe that it's quite there yet, it's very close, and will be in the short term. There's no point for most software vendors or developers to painstakingly, and expensively, port all of their applications to a new architecture and/or a new interface.
Why would you want compatibility though, can Surface Pro 2 run Crysis and why would anyone consider running software that isn't optimised for a touchscreen on a touchscreen based device?
Most of those apps only require recompiling for ARM to get them running anyway, Outlook 2013 on Windows RT 8.1 is the perfect example.