There's a difference between being serious about a product and being serious enough to do what it takes to make the product succeed. Apple has set a high bar of tight hardware/software integration, where the software is hand-tuned to take advantage of everything limited mobile hardware has to offer. The market expects nothing less. The Apple model works because management is willing to control both sides, and the Android model works because everything is relatively open so the software devs can play directly with the hardware.
> there was a limited number of things we could do
No one is blaming you or your team. I'd blame the lowest person in the company who had the ability to install beta versions of Office on beta versions of Surface.