Yes, development spends a lot of time trying to figure out where a set will take the metagame, but by that point the design is already handed off
Yes, you can get an additional end step
Whats more, it creates 1/1 Human tokens, so you can have a human typal subtheme, preferably with gold cards
Again, this saves a lot of time in this process
The built-in exile at end step or leaving the battlefield clause on Unearth is another key limitation, which is why your best targets for this are creatures which can have massive impact inside of one turn
It also comes with the chance at opening some great new cards for Magics premier multiplayer format, Commander