Mail's makeover wasn't pointless. Putting the mailboxes in a draw was a complete contradiction of the modern UI guidelines. Source lists belong in a split view. So putting them there was a correction, not just a cosmetic thing.
And as for the toolbar buttons, I don't see what the big deal is. They're just buttons. I don't understand how anybody could either like or dislike them. They're so inconsequential.
Then again, I've seen artists spend hours designing replacement application icons because they thought the vendor-provided ones were ugly. So who the hell knows.