I am currently using this software to design the first of _up to_ 6 boards for a project which will fit into a 6" x 4" x 2.1" ABS enclosure _(Circuit Specialists Part #PB-4P)_ when finished. This project is fairly simple in terms of board packing (The 6 boards slide into slots molded into the enclosure, with 1/8" space at the top for slightly crushed-down wiring), so the feature isn't really necessary right now, but I imagine it could be very useful for a few other projects some other people are working on right now.
As an added feature, this doesn't sound like it would be too complicated (at least not compared to the 3D view itself), since the 3D view already has the models of each component, plus a procedurally-generated model for the board itself, and the "Export .STL" button would only need to merge these models into one, then encode it into a file which is then saved to the user's computer through their browser's download function.
Firefox
82.0
Ubuntu
EasyEDA
6.4.7