2D or 3D for Isometric Multiplayer?

Hello,

I am trying to weigh pros and cons of having 2D environment/props in a web-based massive multiplayer game, and having the same in 3D, considering that player avatars will be simplified 3D meshes (~100 polygons). The game will have a still camera and isometric view which will not allow for much detail on said props, so they could be easily broken down to visible planes.

Furthermore, the idea is to have procedurally generated maps at a point, which makes me think that maybe 3D has the potential to be more modular?

I was just wondering if there would be thoughts on this, or if anyone has experience with something similar and could point out whether rendering simple planes in a web-based game might actually make it unplayable.

Many thanks!