From my foxhole point of view, I believe that the introduction of heavy transport planes (C-130, C-17, C-5, CH-47, UH-60, etc..) would deter DCS from its original concept of being a DIGITIAL COMBAT SIMULATOR. While these airframes would be fun to fly, especially in the highly detailed terrain areas that have developed, I feel as if they would take away from the realism of COMBAT flying and engagements. DCS lures you in based on the ability to operate a multitude of aircraft from around the world in a combat situation and learn, through trial and error (mostly error for me ), how to conduct missions. These heavy aircraft would provide zero combat experience to the game, but rather just another platform to fly around.
Now if DCS, and its third-party developers, would start developing heavy bombers or Global Hawk / Reaper, this would provide an additional level of real-world combat realism. Pilots would then be able to act as Aerial Recon (CAS or ISR) with the Global Hawk or Reaper calling in targets to be engaged by the Apache or fighter jets. The heavy bombers could follow F/A-18's or F-16's into the battlefield as they conduct SEAD missions ahead of a major strike on the enemy compound. These types of platforms would provide better additional realism to the game than additional platforms just flying around in.
If you are looking for an environment where you just wanna fly a Heavy Transport airframe from Point A to Point B and "simulate" delivering cargo or troops, then use MSFS or X-Plane.
Thank You
Maybe even an AC-130 Gunship as well?!