We get tin cities and more but  airports get replaced with much less convincing stuff or generic fluff.

I expect PG cities are affordable because there are not too many of them. PG airports would be unaffordable because there are much larger numbers of them.

PG cities make sense to MS because they show the scale and beauty of their digital twin. Not so much with airports.

PG tends to look decent from far away (while flying) but much less convincing up close and on the ground, where airport image quality matters.  PG for airports is quite simply a terrible idea.

Their world hub concept needs to evolve so that it works similar to XPlane’s gateway system.  Individuals can basically craft an airport to look almost like the real one, using a vast array of default assets.  
 

But then again, sales of third party airports would drop if the defaults look too good, so less money for Microsoft.