Jumping with a full length cue is fine, but there's an advantage given to taller players or players with longer fingers. The shorter jump cue somewhat equalizes that.
What about limiting the number of times a player can use a short jump cue in a tournament? I've seen InsidePOOLmag's video on youtube between Nevel and Strickland where they were allowed 2 jumps with a short cue, and no limit on jumping with a full cue.
Personally I think it should be up to the tournament directors. When Filipino players came to the US, they pretty much took the art of kicking and safety play to a new level. I see the jump cue as something else to take the game to another level.
Jump shots are jump shots. If jump shots are OK then there's no reason why jump cues aren't Ok as long as they have a leather tip.