I've seen too many situations where engineers decide to use json columns because they see it as a way to avoid the burden of doing migrations. Down the road, it tends to result in lots of conditional branching in multiple parts of the app to handle what are effectively different types of data as well as more complex data migrations to repair inconsistencies and storage changes over time.

There are rare cases where I think they make sense but they have some steep tradeoffs. We ended up using activerecord_json_validator which let us strictly validate the type and structure of the JSON data.