As someone who spends an insane amount of time supporting novice sysadmins, I think it increases the complexity very much. It takes an enormous amount of work to support just the one dead-simple foolproof configuration. Even managing a two-container install and knowing to do replace app with web_only (not to mention knowing how and when to update the data container) increases the complexity at least 4 fold.
This, I think is the big win.