Hi Talon,
sometimes it's not just sheer laziness. I tried mission building in the early CFS2 days and I immediately discovered that it was not as simple as described in MS' CFS2 manual. My fights with an extremely touchy MB were epic, as it doesn't take tweaks and addons very easily.
Building a straight take-off/spawn and meet the enemy/dogfight them/return to base mission, using only stock planes, was not a big deal. The few missions I created with that simple logic became boring after two or three times at the most. Besides, I noticed that my home grown missions went always the same way, while the stock ones, spiced with event triggers, hidden targets and so on, have the capacity to take advantage of computer applications inner decisional "if-then-else" logic. This makes those missions evolve differently almost each time one flies them, which gives CFS2 its greatness.
But such concepts necessitate a deeper knowledge about how CFS2 and MB work to create interesting products. When Cody Coyote released his first, great mission building tutorial, I downloaded it and devoured it. At the time, my CFS2 knowledge had increased but I started realizing that, even with Cody's manual, developing a good mental picture to make good missions was not everybody's cup of tea.
Then the first, historically correct oriented campaigns were uploaded. Those implied one heck of an accurate research job to do things right, on top of everything else, and I became more and more involved with other aspects of CFS2. I simply gave up mission building because others, you among the top-notch ones, were doing a thousandfold better job than I was doing.
I imagine others came to the same conclusions, by the same token I agree with you that, without new missions, the interest in CFS2 may decrease and become part of the end of it.
I only hope this will happen as late as possible, and other people will become interested in mission work. I am still patiently waiting for improvements of CFS2 announced over the years, some of them became reality like Rhumbaflappy's corrected mesh. Scenery is one of the biggest promises, like SdC' Autocoast tool, which should bring CFS2 close to the visual levels of FS9 or even FS10. The end of a generalised interest in CFS2 potentials would inevitably mark the end of other improvement projects.
Cheers!
KH 
