The only thing that was wrong with it was that they made it so you can still get all assists but get the refresh. Now it's changed and you have to choose between starving your team mates of kills, or being useful. Tbh, I'd rather not have one on my team that just sits at the back waiting to snipe kills and if I did I would assume that the enemy has more chance of losing, unless my team was already losing anyway to other causes.
People don't have to sit and wait to use their ults.
He can pull and deal out damage during the fight and finish someone off when they get low. In fact, doing this will increase his ult's damage. He's also useful if he has more kills than the tank and support, considering he does stuff during the fight such as pulling, aoeing, autoattacking, etc, and not just waiting to snipe a kill as you described.
If they're just waiting to last hit then it's the player, not the champion.