With each new generation of the engine, it gets harder and more time consuming to develop addons that look as good as the originals : see the MI24 in game ? How long will it take for the community to produce addons of that quality with all the great shaders and details ? A LOT !!!
I know, I worked on a Hind before, and though it's rather easy to get the rough shape right, the time you spend on fine tuning the details, UV, textures, specular, normals etc... is sickening (and don't get me started on the cockpits).
For OFP, it was easy to make something that looked as good as the original (blocky geometry, simple low-rez texture, lousy UV), for Arma 1 it's a little bit more tricky (more details, more attention to UV, multi-stage materials, higher quality maps), for Arma 2 it will be a pain to match the quality, and only professionnal-grade modelers and texture artists will be able to output game-quality mods...
That's how things go... the better looking and realistic, the more time consuming and complexe it will be. Otherwise, simple OFP-ported addons will look like a sore thumb in the lush and detailled gameworld of Arma 2.