I will grant that strong_migrations is really cool, and data migrate is nice but not really that hard to implement yourself if you need that. Bullet however IMHO is a way overly complicated way to solve for N+1 queries. I would argue that eager loading associations by default is wrong and a thing ActiveRecord shouldn't do at all.

You can opt in to preloading with Ecto when you consciously want to make the tradeoff, which I think is a better default approach.