Like most Magic: The Gathering cards, the value of Morph depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Masters 25 Tokens)
Being a mana cheaper than Conjurers Closet does mean you lose the ability to steal creatures (they come back under their owners control, boo!), but its still great to have this card
"My 61st card is a tutor target for Trophy Mage, and it's better to have it in my deck so I can find it than not have it at all." That's doubly making your deck worse: you're playing a card you apparently don't even want that often and reducing the chance you draw the cards you want more
Still, there is something deeply satisfying about a Commander that swings for an uncontested 12
Modal spells like You Come to a River sound perfect for this
Most of the time, these cards are all high-value so players can draft incredibly strong decks