We keep going on about the "gestation period" for FSX.
People seem to be forgeting how long some of our (the royal our) stuff took to get out. I'm pretty sure that if Rick or DM had something out within 9 months that was quick. And I distinctly remember the Argosy taking well over a year.
Captain Sim (only mentioning because they where one of the obvious ones) took years to bring out new models.
If we're using AS as a bench mark, yes, maybe it has affected the way they develope models, for the better I'd say, in that the quality of some of the new stuff is very high.
Or maybe all those who spent the first year birating FSX without trying to make it better are now on the back foot as its now a great sim, with more and more people realising that since SP2 at least, a lot of the ranting about it was just that, ranting. The past few months have seen several of our number buy it and be quite happy with it, on very modest PC's.
There were always a hardcore of developers who took the plunge first, when the sim changed versions. I remember many of us on here waiting patiently for DM's VC10 and Trident updates from 2002 to 2004. The differences between 2002 - 2004 where less in the visual side, but more in the FDE / panel, so many where more forgiving of 2004 as the aircraft still "looked" great, even though some of their characteristics where far from it.
The one thing we are all forgetting, is that we (the users) have become much more decerning, not just in FSX, but what the developers can now do in FS9 is much more advanced than in the early days. If you compair DM's VC10 with the Comet for example, many of us would expect a new VC10 to be as complext as the Comet (VC etc) (Personally I'd just be happy with an FSX VC10 and the old panel... hint hint

)
Anyway, in short, its natural evolution, and once you learn the tools and have a consistant FSX platform (i.e. SP2) I don't think it takes that much longer to build an FSX model, certainly not by compairing Ricks Argosy or 748 with the Hawk, they all had similar development periods.