Time and money to develop. Its a double edged sword. The bread and butter is real time tactics game. That makes cash and its good. PLayable vehicles and such takes quite a while to make. From experience for the time to make 1 tank inside and out I could make 3 or 4 external only vehicles. And less headache by a mile to configure for game. So if you where to do that you get way less game for tactics sort of thing. You also muddy up the game and perhaps add in a ton of bugs.
BUT.... taking assets of real time game and converting into a tank sim or something that is stand alone might make sense. After the tactics game is done. BUT then you take time away from DLC's and such. But the money to develop the playable vehicles is the real issue. I would LOVE to see this 2nd approach at some point. The price might have to be HIGH per vehicle. Assuming more than one. But keep in mind that the previous tank sims have not made much money. They are freaking excellent sims but not many bought the things. But I could see it working......... Just risk. It could hit a sweet spot if sold via steam. I really think there is interest in some legit vehicle sims and or command/control from a vehicle. If marketed right with a budget and based of assets that are mainly payed for through the real time game I think it could pull out a decent profit.
This is just my opinion.
But MIUS should be focus as a tactics game.
