Well, people DO need TIME to make mods. If you think that perhaps 5% of the JK2 community makes mods that they plan to one day release (a generous estimate I'm sure) then perhaps they all are on similar schedules (hypothetical) it takes them a few days and they release a simple mod. Then you have nothing for awhile, and then they try something bigger, which takes a few weeks. Then they release that.
A lot of projects are so optimistic and huge they never get done, but usually those are dead in the water before a whole lot is accomplished. You know what I mean, the huge TC's that plan to change everything about the game and be packed with levels, and spend months getting a team together and releasing a few skins. That's okay, its how people learn from their mistakes.
But the point is that you can't expect mods to be released every single day, each better than the last. If you just mean skins, sure, in theory somebody could make a new skin every day. Or a small level. But good mods take TIME which means you have to wait, unless you're the one making the mod.
Again, doesn't mean the community is dying off. JK didn't see any major Conversions/Mods for a long time. Release was very sporadic. Much of the really amazing stuff was released YEARS later, after people had finally become comfortable with the engine.