Opening a login in the browser extensions, mobile app (iOS at least), and Windows 10 app all open it as view-only at first, with editing kept behind a button. The My Vault website however opens the login right up in editing mode which frankly just makes me nervous about something changing unintentionally and saving accidentally. Would it be possible to make the vault website match the other apps by opening items as view-only at first and adding an edit button?
Yes, I would definitely like to see this happen. It could be as simple as adding a readonly attribute to all of the entry sections on screen and have a button that removes said readonly attribute via Javascript.
Two years later… 
I’m with you! It would be great to open entries in read-only mode in the web vault to prevent them from changing.
May be you should add an Edit-button to change entries. This is something I liked in “1Password”.
And because it isn’t able to copy username and password directly from the entry list you have to open an entry. So it could happen that you change that entry although you just wanted to view it. 