So why do we need e2e encrypted messaging? Why do we worry about the "secure" part of messaging? One of the main reasons for me is, it's hard to trust a centralized authority.

Can you trust your information stored at your messaging app's servers stay secure forever? Can you trust that company to never get compromised? So yeh, they go through all the hassle of making things "secure" but attach everything to something(phone number) most of us can't get without revealing our actual details. So yeh, its ridiculous to go through all this hassle to make things private and secure, but force people to use something that de-anonymizes everything about them.