Ah, but historically using simple geometric patterns has lead to a great deal of incidents.
For instance prior to the creation of the standardized symbolism we have today in the military they used simple geometric shapes to explain different hazards. This was not memorable and was easily missed leading to a great deal of trouble.
As for it being too complicated and so on, I pose you this.
The
standard biohazard symbol can be made with a piece of charcoal and some string by a complete amateur. It is technically not complicated, is rotationally symetrical, and would (probably) have no inherent meaning in the planes. It is easily recognizable and striking as well, hard to miss and easily remembered.
And it has been used for around a hundred years in RL.
EDIT: Added a link for visual aid.