from other mod projoects i've noticed that there's never a lack of 3D artists. maybe because creating 3d models is not an art at all and requires not a lot of imagination -- so it's more nerd compatible. back in the low texture size days people who could do good textures were really rare. now with photo based textures and shader effects it also became a technical instead of an artistic challenge, so there's no lack of textures either. The 3D models typically also got shared between games/mods, further reducing the workload. (Well, i guess more than half of the repositories are filled with weapon models, but there are also plenty of buildings)
i don't want to suggest making* simutrans 3D, i just think that creating the 3D content is not the real problem.
but of course going 3D would just mean swimming with the stream, excentricism is something i value very highly. And there's quite a lot of content in the available paksets.
the players response during the switch from painted 2D to modeled 3D was mostly negative, it just looked really ugly with the primitive 3D back then. being excited with new technological possiblities has also been a factor in game industries, i think.
* the key word is also 'make' i don't do anything, so i don't have a right to suggest anything anyway.