Is 3D necessary in Heroes 3.59?

"unnecessary" 3D graphics in 3.59

Actually, there might have been some elements of it in 3.59. But redrawing the entire game is no longer Heroes 3, and not just a mod, but a new game.
There is also the factor of personal time, and spending it on a very large project that many people might not like.

HotA and WoG are such different projects. And if the goal of WoG is to implement various features in Heroes 3, then HotA aims for classic gameplay, and classic Heroes 3 cannot have 3D.