I totally agree with your points. The current difficulty sure feels like 'Hard' rather than 'Normal' since the customers just rush. On day 22+ I guess the waiting time is only 40seconds and evolving from copper to Tin is the most hardest part in the entire game since you earn so damn less profit. Even a Fancy Polearm with A Greatsword gives you nothing. And the Quality thing (Shift+LMB) doesn't do anything for the price. It's basically useful for us to equipt eg: A Copper Pickaxe With 30 quality might mine Twice as faster (my assumption) but for now the quality doesn't even effect the price I think It'll be implemented in a future update tho. Although Mining Tin with a copper pickaxe or any type of pickaxe mining a level further feels too easy. I'd say instead on 'Normal' and 'Easy' Mode the waiting time of the customers and Price of Ingots should be reduced.
Well those are just my thoughts tho.