Well, I love the conspiracy theories you have postulated. I suspect the problems are the result of much more mundane realities. What follows is my own private conjecture about the situation.
MVPs get to meet the Microsoft Office for Mac team occasionally, along with the Office for Windows teams. Size matters. There are thousands of Office for Windows employees and a relative handful of Office for Mac employees. I think the #1 core problem is
there simply aren't enough programmers and program managers at Microsoft who know how to write code for Macs. The door is always open. They ask us to encourage anyone who wants to work for the Office for Mac team to apply to Microsoft. There is a world-wide
shortage of programmers in general, and there's a critical shortage of programmers who know how to program on the Mac. Finding and keeping (especially keeping) programmers and good managers seems to me to be the #1 problem.
Then there's the general opinion that the web and mobile devices rule and the desktop is dead. No one wants to program for desktop applications any more. iOS and Android is where the action is. You would think Windows Phone would be attractive to developers
who know Windows, but not so much.
Email is considered a dinosaur. Who wants to have on their resume they helped write Microsoft Outlook? Sure, it's used by millions of people every day, but text messages are the rule today.
I can't rank #2 #3 #4, etc. There are just some other factors that seem to come into play.
* Mac OS. It changes like the wind. Trying to keep Office running on each and every update that comes down the pike is a huge problem. Sometimes I think Apple deliberately messes with Mac OS to screw Microsoft. For example, the next item in my list...
* Sandboxing. Microsoft adopted sandboxing to keep Office for Mac "Mac-like" and because Apple won't let Microsoft sell Microsoft Office in the App store unless Microsoft goes along with Sandboxing. Sandboxing crippled Microsoft Office. If I were looking
for criminal behavior of a monopolist, I'd be going after Apple about sandboxing and their strong-arm tactics about getting apps into the App store.
* Cost containment. In a sense, maintaining Office for Mac and Office for Windows is duplication. You have to invent everything twice. Since Office for Mac sales are less than Office for Windows, Microsoft is keen on keeping the cost as low as possible.
This, combined with not enough staff, is a big problem. Expensive to make features that don't get a lot of use are left out of Office for Mac. For example, Object Linking and Embedding (OLE) is very limited on the Mac.
Which results in a very weak version of Excel for Mac. I consider it to be only about 1/3 done. If and when the promised Visual Basic Editor ever comes along, then I'll consider it to be 2/3 of the way. When the missing SQL and data components finally make
their way to the Mac, then I'll say it's complete.