You never have enough diamonds in survival. So you still need to use iron tools occasionally. Sometimes even stone tools!
I would not waste my enchanted diamond armor if I go in some random cave. I put iron armor in case of accidental death. I will use diamond tools and armor for purpose - situation I get guaranteed reward (fighting bosses, woodland mansion, nether fortress, etc). So, Minecraft is balanced here.
There is HUGE "steak problem". You don`t need chickens, you dont need pigs, you don`t need potatoes, you don`t need beets.
All you need is to find two cows and raise wheat to feed them. Done. You can do this on earliest stages of the game. So other types of food completely pointless (except golden carrots). This must be fixed.