You will read a lot about how this improves stiffness and heat sink from motor these are all true but when measured the level of rigidity increase and torsional deflection decrease in the chassis is so minute it hardly needs mentioning.
The greatest performance increase these add is in the center of gravity shift forward and heat sink.
But the reason why you must have these is for when you are changing belts! No more trying to hold nuts in stupid little holes when trying to screw in bulkhead covers. DON'T USE TO MUCH THREAD LOCKER.