I had trouble understanding what you meant by this because the question-inverted word order doesn't appear to match the lack of a question mark. Did you mean "that doesn't mean..." or "doesn't that mean...?" So I'll try to reply to both interpretations:

Does being initially exclusive to Microsoft's platform (Windows) disqualify a game for a later release on Microsoft's other platform (Xbox One) once the game's developer eventually qualifies for the ID@Xbox program? If so, why should it?

The 1987 video game Contra by Konami was originally exclusive to a non-Microsoft arcade platform. In 1988 it was ported to the Nintendo Entertainment System, another non-Microsoft platform. Yet it got a port to Xbox Live Arcade on Xbox 360 in 2006. Did it get a pass because of the 1989 port to MSX2, a Japanese platform that shipped with Microsoft BASIC?

How many MB per month is that? If unlimited, then where do you live? And how many MB per hour does RDP or VNC to the EC2 or Azure holding your IDE use?

In my experience, Wi-Fi handoffs are not rapid enough for use while a passenger in a bus or other vehicle.

A lot of parents are more willing to drive their children around during bus outages than to provide cellular Internet access for their children to do programming homework while visiting somewhere that lacks usable Wi-Fi. Besides, how ought an iPad+keyboard+cloud+cellular user to back up the data stored in his cloud services account in case his cloud service provider goes down? A PC user can just plug in a USB flash drive.

California is one. The Pacific Northwest (Washington and Oregon) is another. So is the Dakotas (North Dakota and South Dakota). And there are plenty of other Sweden-sized tri-state areas.

A Windows laptop is less expensive than the cellular Internet subscription needed to connect a tablet to EC2 or Azure while away from home.

Perhaps the point is to avoid flying to the client's desk in another country.

It's not the same thing. Bing Videos is a search engine, analogous to the Google Videos search engine. YouTube also offers hosting for videos uploaded by users. And in fact, for one random category I just viewed in Bing Videos two minutes ago, a large number of the videos were hosted on YouTube. Bing Videos is to Google Videos as what is to YouTube?

This was not true in the early days of Windows Phone. Developers had to pay $100 per device per year to unlock a Windows Phone 7 device for sideloading apps, the same policy that it had applied for XNA Creators Club on Xbox 360. When did Microsoft change this policy?

Trying to understand how Microsoft defines "exclusive":

Then how did any of the Xbox Live Arcade games, which were originally exclusive to proprietary arcade system boards, get released? Or are these all in the "too large to be intimidated by them" category?

My taste appears to differ from yours in this respect.

Which makes "a lot of things" useless to people who need to run a compiler and its output. The iPad and Surface RT are among them.

I guess I made this mistake because WhatsApp has been fairly aggressive over the past week at blocking third-party clients, and I seem to remember that Snapchat "expressly prohibits" their use.

Agreed. And with programming classes becoming more widespread in high schools, a lot of parents will have to upgrade their kids from an iPad to at least a Raspberry Pi if not a full-scale PC.

This is where my taste differs. During freezing or wet weather, I ride public transit to and from work, and in my satchel I carry a 10" laptop on which to work on hobby programming projects.

Then why doesn't each 450,295 km^2 chunk of the USA have Swedish-class Internet?

Then what's the cheaper way to cross non-subscribers' private property to reach subscribers without tearing up roads?