While there is a crowd out there who simply want to get their hands on every foil card a set has to offer (I know a few players in my local area like this), there appears to be a more significant attraction to chasing the exclusive, expensive rare cards that these Collector Boosters have a chance of containing
Get deck evaluations covering synergies, mana curve and win conditions, and chat about rules, interactions and sideboarding
Of course, that isnt enough to win the game, and Ketramose often leans on flicker effects to handle that
Gaining benefits from the cards you control or have used is the added value that can make a deck strong
Overall, it's just a really strong piece of Equipment that can break the game if left alone on a creature for too long
If you take their only two drop play for one mana, one card and no life cost you have actually gained tempo