Tweak World height for easy user interface and ore generation aswell

I was just wondering wether the coordinate '0' could either be at grass level (floor level) or the new bedrock floor as of 21w06a to make it easy to understand for new players as it will be confusing for them to be on -16, etc etc. Also, will the new world height effect the nether (and the end if that's possible)?

On this point, i was also wondering if ores (specifically diamond for this point) became 'rarer', should ancient debris become slightly rarer than diamond ore for game balance, (also seing as some devs agree that minecraft has become easier over time.......not that this will fix it majorly or anything, but it will make the game just that slight bit harder)