Think about it: It's a little rarer than iron, and it would perfectly fix the progression issues.

Structure loot would change a little. While nether portals and bastions would have the same loot, ocean monuments would change their 4 nether gold blocks into overworld gold.

Overworld golden apples could have special niche status effects, like being able to see in lava, or complete knockback resistance.

Edit: Just realized that iron and diamond are already very close in armor units. It could be slightly buffed, but still be lacking in armor toughness.