Microsoft wants to become a devices and services company. Microsoft was a software company, but not anymore. They are in the process of changing...
Office on iOS will come when Microsoft admits that it lost the consumer market to Apple and Google. Only then and not before...
They had a chance to become that back in the mid 2000s and they didn't do it. Instead they let companies like Dell, HP, Compaq, etc kill the PC with their ridiculous machines that crashed all the time, failed, etc.
MS had the opportunity to copy Apple and make their own line of Desktops, Laptops and all in ones and they didn't do it. They had a war chest of $$$ and didn't invest it wisely. They could have made killer MS product like and did the 3 of each. 3 laptops (low mid high), 3 desktops (low mid high) and 3 all in ones (low mid high). Sorta like Vizio is doing. But MS had the OS behind them and the ability to make a 'flawless' Windows experience by controlling the hardware AND software.
Ballmer as usual failed to see this and came late to the party..almost 10 years later. Then to have another chance to get ahead, they sat around and joked about the iPad and how it couldn't replace the PC, not realizing that the majority of desktop/laptop PC users never needed those machines anyway...they needed a social machine to email, browse, watch movies, music, socialize and some minor gaming. What did they do? They waited almost 2-3 years to get a tablet out and in the process put out a crappy machine and again allowed 3rd party vendors to ruin the experience instead of just focusing on their OWN tablet and making it themselves and ONLY themselves.
They've lost the consumer market already. Have for a while.
I mean the damn blueprint is there..it has been forever. Control the hardware and software and make a user experience and eco-system that people don't want to leave. And they didn't do it. And it's on Ballmer for that.
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The problem is that Office is a way to keep Windows a viable OS for everyone from home users to business (especially the enterprise!) through OS lock-in. If they offer Office on every platform, the OS side of the business would drop a gold brick out their backsides and simply not allow it because people might not feel compelled to have to buy Windows.
Unfortunately that doesn't make much sense because they offer Office on the Mac. It would make sense if they never did offer it on OSX. So it's not like they couldn't offer it on iOS. Their goal is to sell software and their Windows software sales are plummeting.
It's really simple...most people aren't feeling compelled to buy Windows ever again. The 'strangle-hold' MS had on consumers is over..it's been over since late 2011 with the iPad 2 gaining huge dominance and growth and ever since PC sales have plummeted every quarter.
Adapt or die. Their adaption is to take their #1 product, which is actually Office and get that out there on iOS.
You will also see game companies, like Nintendo move to iOS and ditch hardware, especially their mobile game division.