I think strong-gripped static grabs are quite important to assist in developing one's structural alignment and power generation for Aikido waza. This may be done by exercises, drills or during the practice of kata (waza) during normal class. Ones ability is readily seen in randori (especially resistance randori) where ones structural alignment, power generation and distribution can easily collapse if it has not been trained during "static" training.
Static, strong grabs also help one understand the precise relaxed movements required to allow Aikido technique to move past another's resistance by combining with and realigning the attacker's bone and muscle structures to weaken the effects of the "strong-gripped static grab" to facilitate kuzushi and technique.
Just my 2 cents.