Some people have requested the ability to turn off all units so it's strategic icons only for performance reasons. Wouldn't we be able to create a model that's just a box or something and swap out all unit models to just the little box? It wouldn't be exactly the same as strat icons only, but it'd be close and would help out people with low end computers.
The model includes bones, so it's not really possible to do easily (you'd need a unique "box" for each unit). The absence of a bone specified in the blueprints often causes the game to crash, depending on what the bone is for.