Well when you want to comeback home , you don't want to come across a clone of yourself who already married your lover, had kids, settled down and your ex lover says "you were never around what did you expect and besides it's not like I'm cheating on you because it's a copy of you". I'd imagine time travels faster when you are out exploring deep space and having a blast while the copy of you is living his life on earth. Yeah, still worth it.

The Agent Smith problem. Right now if an entity in meatspace wants to copy itself it has to breed, and for anything complex the copies are not the same and have to go through a growing process. With copy teleportation it's not really any different than Ctrl+C/Ctrl+V on your computer. As long as you have the energy you can build entire armies of yourself. There many be plenty of good scenarios for this to happen but I can think of far more downsides.

Play Sims 4 with the "Get to work" expansion. Having 8 me's in a house is a real problem.