SakashiroRenraikuPG and Solo were tacked on to placate those that wanted an offline mode. They are legitimate modes, they are not the original vision.
If anything was "tacked on", it's the always-on requirement to ED's offline mode that was originally promised during crowdfunding.
That's not tacked on, that's a necessity due to how the game evolved.
Requirements change in development and that's one of them ^^