Yes, the current state where tanks puff smoke like steam engines is ridiculous.
I believe it was done for the benefit of CAS as it makes tanks easier to spot from the air. The majority of map changes are to the benefit of CAS so it fits the strategy they seem to be following.
I think this would overall be an interesting change. Also, turbine engines should be completely smokeless, so I would also like to see that added along side this.
There are a lot of things that gaijin does that I don’t make sense of. It seems that in the game all the engines don’t have good combustion. A realistic thing that makes some sense would be that the tanks made the smoke they do when the engine module was not researched, and when researching it they made little smoke, thus giving meaning to the module that is related to the engine review. In stock form the engine has no maintenance so it has poor combustion, and when unlocking the engine module, the engine is checked and working optimally, so it has optimal combustion and does not generate so much smoke from the exhaust.