Because you cannot achieve a RATE 1 turn inside 30deg AOB above 180 KIAS. Usually limited to 30 deg AOB at most levels ( it can be less depending on the situation and a/c type ) and at our speeds it's not possible achieve rate 1.
So we never use/refer to rate of turn or have a display of it.
Bank angle is more of a concern with reference to maneuver margins above stall.
On a Boeing there is a slip/skid indicator under the sky pointer at all times.
On a Airbus it is also a Beta target on t/o with an Engine out.
Nothing magical here.