The thing about conversion mods for 3D games is that by the time they are done (if ever), the engine they are converting to is already so old that it defeats the purpose of conversion. I'd rather play the original (well, not Oblivion) if it is still playable and add some enhancemets to update it a bit. You could argue that some things, like Morrowind's combat, can only be fixed by conversion due to engine reasons, but still I don't think that switching it to Skyrim's systems would do the game a favour.