GTA IV

I know its rather old now, but I felt like playing it today with Tdub. While playing GTA IV I noticed EVERYONE had some sort of mods. Many of you who have modded vice city and other games like that, then you realize how big the modding community is. What happened to GTA IV? Is it that much harder to code? I would love to see some Mutli-Theft auto for it (Yes I know it already has multiplayer). I feel that the multiplayer with the game was rather...lacking. Even role-play servers was pretty sweet for GTA SA. Perhaps with GTA V it will fill in those gaps that GTA IV had.