They're a broken crutch mechanic that promotes lone wolf gameplay, more than teamwork. Used primarily by heavy assault mains who arguably already have the advantage in any given 1v1 firefight. Removing them makes medic support an reliance on teamwork for survive ability more integral. Restoration kits are completely fine as they function similarly to a medic's medic tool in healrates. If medkits were removed I wouldn't even care if they increased resto kit effectiveness with a longer duration.