In a meatspace game, I usually only draw the relevant parts of the map once combat starts. And drawing by hand on dungeon tiles is much easier than drawing using the computer, at least when using a mouse. If I were to draw battlemaps by mouse at run-time, that would be a massive pain both for me and my players.We use Roll20. Put the whole map on the screen and cover whatever the PCs can't see. As they move reveal the new areas of the map. It's not hard. It's not perfect but it works.
It's the insistence that the VTT be a simulation that's the problem...and what drives players towards "needing" a 3D VTT. Do you spend the extra time in meatspace games to get a mobile light source that shows through windows and doors? That only and exactly shows what the PCs' light source would reveal? I'm guessing no. Or do you just reveal the whole next room by pulling back the cloth or whatever you have covering the map? I'm guessing that's what you do.
So the "extra" work you're complaining about and dreaming a 3D VTT would solve is a problem entirely of your own making. You've created the problem and want the machine to solve it for you. Why do that? You can run it in the same way you likely run meatspace games. Just because the VTT can do something fancy doesn't mean you have to use it. All that extra work for so little gain.