Sometimes you'll trigger it, sometimes your opponent will trigger it
Essentially, tapping your creatures for mana makes developing your board trivial, especially in go-wide decks
Watermark: Conspiracy Seal Illustrated by Karl Kopinski Standard Not Legal Alchemy Not Legal Pioneer Not Legal Historic Not Legal Modern Not Legal Brawl Not Legal Legacy Banned Comp
Eldrazi is a deck designed to beat down with large creatures
He doesn't copy whether that permanent is tapped or untapped, whether it has any counters on it or Auras and Equipment attached to it, or any non-copy effects that have changed its power, toughness, types, color, and so on
Having a handful of cards that improve the overall quality of cards in your deck will help your decks achieve a higher power level and maintain more consistent games