I'll be honest, I think this is in preparation for the new map, and people will have little to no minas carried over.
Back in the day, every donation package used to come with minas, and bedrock got 80,000. Then that was cut in half, and diamond got half of that, and no other packages came with minas. There used to be private mines instead. I'll be honest, I seldom use power of the earth to go mining, but it's fun building below 'normal' levels and making things.
On the bright side, there shouldn't have to be a second map reset, now that MC is 'officially released', so once the world gets through this one, it should be smooth sailing.