kompressor does engine updates, like the brick oct tree, physics and shaders, Badspot does all the torkscript work (I think) and creates content for the game, Rotondo creates some add-ons that are included by default, and the community creates tons of content that would be useless without the work of the first two.
So, you can say, both are equally important.
Without the development team we wouldn't have blockland, without the modding community blockland would die.