T1 engineer spam often results in pathfinding problems and more lag. If we encourage concentrating bp in t2/t3 engineers instead of t1 engineers, that would often be a boon to pathfinding and lag reduction.
T1/T2/T3 engineers presently have equal efficiency of build power per mass. If we change it so that bp/mass efficiency increases with increasing engineer tech, then people would make fewer total engineers (concentrating their bp into higher tech engineers) on average.