I don't trust E2EE in a Meta product anyway. I assume if they offer it, it's to limit their own liability, while still probably having the ability to gain visibility into one's messages should they feel they need to.

I don't mind this, people who want E2EE can/should use Signal (which has its own rough edges but is certainly better than Instagram's in-app messaging). The E2EE rollout on Facebook has caused many people to have issues sending and receiving messages.