Alex, these sceneries are made by individuals in their spare time for fun. They aren't made to a specification, nor are there any commitments to update them over time. For those things you must go to the payware software houses and give them your money. You may then demand a certain level of service. You can't do that when you don't pay!
Making scenery from nothing is a complex business that demands a lot of time. However, through the generosity of several people at MAIW, the components that make a believable airfield are available in the Download Hangar, and with the assistance of the ADE program (available
here) you might like to try it - and let us know how you get on!
MAIW does not yet develop for MSFS.