Comparing one game to another, one on one, is apples and oranges of course, unless you've had a look in the kitchen with both developers and know exactly how both of the games are constructed and working, etc.
What works a certain way for one, might not do so for the other, and vice versa.
And it's not just about 'making ships smart', you have to put every single rule and regulation to work. It's not like some drone in a shoot-em-up that has 6 ways to attack, 4 ways to defend and 3 ways to fall to the ground when killed. It's very complicated to get all that to function properly. A lot of computing power needed for that. And I don't see many other simulators that have that (granted, I haven't played FSX, but in FS9 and below, the AI is very stupid too, they just follow a path, nothing more.)
VSTEP is 'doing something' all the time, to make the sim better as a whole. The AI traffic is included in that endeavour aswell, I can assure you.
I don't know why people always get a feeling that developers sit around goofing of all day, but trust me, they are not.
Fred