You said it: “It’s not as easy as you think, we’re working on it but it will take a lot of time.”
No sin or tin or whatever cities, DEM, 2,5D… straight answer: not as easy as it seems.
What people want is first of all up to date landscape. A road that’s been there for years but is not in the sim, a whole neighborhood that has been there for almost a decade etc. Why is Bing stone old? Google or Apple are much more up to date, why is MS that far behind? Sure, because nobody uses MS for that stuff but maybe that has a reason? That’s the question that was asked, not TIN, DEM, 2,5D. Jörg is probably not the right person to ask for Bing Maps but MSFS is something like a new flagship in MS’ marketing. It’s astonishing that they seem to care so little.