There was something likes before OBJ File Thumbnail Preview.
The problem of previewing a 3D model is that there millions of possiblities of viewing angles… the zoom could be choosen by the bounding box but if you have model with sparse geometry over an wide are you also may not see very much on a thumbnail. And some models are not very recognizable from a 3/4 view. The best way would to make this mentioned preview automatically but redo this mannually for every model thumbnail which is giving not enough visual information.
But then: how to store the preview? Most (all?) 3D-formats don’t do this. Only for complete scenes the 3D software mostly uses the camera and only for their own format (like blender).
If blender would do the preview i’m sure there would be some nice guys/gals who would blame blender on the bad quality of viewing angle…
There was a script for making previews of obj files… pre-asset-manager time… hmmm i tried this but can’t find it now… ahh yes OBJ Thumbnail Render Script
have to investigate again…