I've been running games for over five years, and yes, everyone and their mother is building a VTT right now. I'm building one too, mostly out of frustration with how much of my evenings prep was eating up. It's called Polymancer: a 3D tabletop in the browser, made to run on weak laptops. No dynamic shadows, and the heavy stuff like line of sight is worked out on the server.
Verticality in 2D is a nightmare. Half the party goes into the tower, the other half climbs onto the roof, there's an archer on the wall, and now I'm doing geometry to get the range. In 3D you just look. Roofs fade when you walk in, walls get out of your hero's way, upper floors show or hide, climbing actually counts. Everyone sets their own camera.
My map editor used to be a separate program. Two to six hours on a map, export, import into the VTT, and then I'd notice what I forgot. Here the editor is the table, so I build before the game or fix things mid-session. Hundreds of low poly pieces that fit together, you can resize and recolour them and paint the ground: water, lava, acid, grass, stone. Building from scratch takes forever when you're short on time, so there are generators for taverns, houses and dungeons. They use the same pieces, and you tweak the result by hand. Players can poke at the world too: open doors, light lamps, move whatever the GM lets them move, or look through their hero's eyes.
Reusing a location meant redrawing it. Six months pass in-game, winter comes, and there go another two hours. Here it's snow or rain in a click, and switching the style changes the whole mood. Same map, and suddenly you're in the Feywild or somewhere deep underground.
Getting people to the table. Some VTTs basically need a technical background to set up. I happen to have one, but nobody should need it. This runs in the browser: nothing to install, players join by link without an account. I also used to spend two hours walking new players through their character sheet, so there's a step-by-step hero builder with hints.
Too many tabs. Want a soundboard? Install one, or stream another app into Discord. Here it's built in and just works. Same with handouts, notes, a name generator and an NPC sheet in one click.
It's not finished, and honestly I'd rather hear what's wrong than what's nice. I'm looking for a few GMs with a group who'd play a session on an early build and tell me what got in the way. It's rough, and it's free. And for everyone else: what would you need to actually run a session on something like this?
Edit, since people asked: I use an AI coding assistant a lot, both for the code and for the Blender scripts that build the models. No text-to-3D or image-to-3D generation, no AI images or textures. ~90 models are from Quaternius (CC0).