Morph isnt particularly strong and doesnt quest for much, but it's cheap, only costing two ink, and since it can come down early, you can set up some great shift plays just a few turns later
It creates a huge army of powerful creatures, which takes advantage of the undergrowth mechanic which gives you bonuses for having creatures in your graveyard
Other times its because we enjoy the art, flavor or effects of the spells in our collection and want to jam them into a deck
"White, Blue, Black, for Part 1, and the rest for Part 2
You can also shortcut Etratas win condition completely by using the other cards which place hit counters: Ravenloft Adventurer and Mari, the Killing Quill