MAKE FIRE PROTECTION IV FIRE PROOF!

Make Fire Protection IV FIRE PROOF!!!!

Making Fire Protection able to swim in lava, able to walk on fire, and the player be undamaged by blazes.
That way it would make so you would rather than have just Protection IV you could have a more useful enchantment to travel the nether, a alternative, that would be more variety so the player could play the game their own way instead of making "meta gear"

The biggest problem with the game is the lack of variety in progression. Improve that and you fix the whole game loop.