I think this change just a referee's job more difficult, when evaluating the legality of a volley serve

Amend / add my prior comment. I don’t think we can visualize the hand knuckles adequately to make this work. And absolutely the rule change about above the waist only “on backhand serve” should NOT be accepted. Above the waist applies to forehand or backhand serves. I do think “above the hip” would be easier to identify than one’s waist (easier to see where someone’s hip bends than waist hidden by clothing), which would also, except in someone very tall, help force players to have the upward arc requirement.