Yes, a topic that was suggested many times before...
Adding the "share half hp" revives back would help in teams, you can help weaker players, or players that don't have any sparks left. Sure, a lot of people say that this would be gamebreaking since you wouldn't have to use sparks. This is wrong, since you will loose half of your health when you share it, so you need to be a skilled player to survive with that, so it would be somewhat balanced(or at least it should be).
The game is now heavily based on the fact that you CAN NOT be carried by 'higher leveled' players anymore. You have to pick up your own Crowns, you have to pick up your own heat, you can't use higher leveled equipment until you're proper rank, etc etc.
Adding this back would just add more people bringing Knights and Squires into FSC or Tier 3 and just reviving them right before the Treasure Blocks or at the end of the Elevator before the level so they can heat their stuff for free.