The ability to easily tap a land is great at slowing folks down by doing it in their upkeep before they untap, or twinned with land destruction and other tempo effects, or to lock out a color, or to tap a land that really needs to be shut down, such as Maze of Ith
Natu () uses Double Colorless Energy to hit for Psychic Weakness, or can be tossed into the Lost Zone freely
This allows you to select a character that has been banished and bring them back into your hand
While I probably wouldn't run out and spend $200 on a playset of Teferi, Hero of Dominaria just to play Blue-White Mill, you should definitely run them if you already have copies in your collection
Being able to get a non-damaged Pokmon back to hand opens up additional possibilities, such as combining Penny with Mimikyu V (Battle Styles) to use Dummy Doll multiple turns in a row