Are weighted jump ropes worth it?

For strength and conditioning, yes, with caveats. Reviewers in r/jumprope and r/bjj note that weighted ropes build wrist, forearm and shoulder endurance and keep their shape better, making cadence easier to feel. The flip side, repeatedly flagged in community threads, is that very heavy ropes fatigue the arms quickly and a minority worry about elbow and wrist strain, so most reviewers suggest starting around 1 lb.