If you’ve dedicated yourself to the 2D line of engines, it’s very hard to switch later on. The time and research investment is massive. At the same time, you don’t have the technology to make truly competitive platforms… and your R&D lab isn’t nearly as useful, since many of its advances are best used with 3D!
If a 2D gaming company has made the investment in an R&D lab, the lab should not have to sit idle for lack of things to do. The R&D lab should be able to do the early stages of 3D research by itself - or find some other means of bolstering their owning company’s technology level.
I agree that the game could use a way for players to be able focussing on 2D for years and then be able to switch to a proper level of 3D later on.
In my opinion this “switch” should require a load of RP and Money in order to make it something considering.