Perhaps there was a dilema at microsoft where in the case of the demo they had to decide on a compromise between showing what was on offer, and trying to get the demo to run on current hardware.
On one hand if they coded in such a way that everything was guaranteed to work, people would have said it was no different to FS9. On the other hand if they code to show what the sim is fully capable of then probably only a very small minority would be able to evaluate it.
Not an easy decision.
My own guess is microsoft want this sim to be a different product, in a class of it's own and from what has been said in other places I believe they really are taking note of consumer preferences. (For once)
I don't profess to be as smart a business man as Bill Gates, but if I were in his shoes I would say there was little milage left in continuing the 'series' the same old way. They've had their sims running now for say 10 years?

Not bad going really, but all things do change. Maybe they realise this in the form of FSX.
As for the demo, I
P4 2.5. massive huge 10 foot display.