Some PA's from the pilots are amateur and embarrassing - usually a hurried gabble using aeronautical terminology that few passengers understand. This can be from both PF's and non-PF's.
One airline operator that I know of had a requirement that after any PA from the flight deck, the cabin attendant at the rear of the aircraft would contact the pilots and advise of the clarity or otherwise of the PA. This had the advantage of knowing if the pilot was using incorrect PA microphone technique with resultant inaudibility to the rear passengers, or exposing a defective PA system which distorted the actual PA. A couple of major airlines in Australia could do well to reinstate that excellent policy.
And is there really any need for both pilots and flight attendants to keep repeating that seat belts must be kept fastened for your "comfort" and safety? A tight seat belt is safe but certainly not comfortable - you can't have it both ways.