By having the ability to return any card from the field or graveyard once per turn, or when it's summoned, gives you the chance to save some cards that may have been sent away or used as tribute for your strategies
Most decks and formats get a little something from these cards
While being a mono-color deck can be a downside (especially for a commander with a grounded effect like The Reality Chip is), blue is one of the primary colors for artifacts, allowing you to play many of the best artifact-focused cards in the game
Sometimes you just want to feel something Creatures (29) 4 Mogg Fanatic 1 Nantuko Husk 4 Dark Confidant 4 Scorched Rusalka 4 Greater Gargadon 4 Mogg War Marshal 4 Keldon Marauders 4 Epochrasite Lands (23) Spells (8) 4 Threaten 2 Char 2 Fatal Frenzy Sideboard And sometimes, youre Antonio De Rosa and just casually top 8 Nationals with a playset of Greater Gargadons to go with the playset of Dark Confidants
It can happen when the enchantment saves the creature or, in the case of enchantments like Unquenchable Fury, the enchantment returns itself to your hand