Obviously the issue with any preconfigured setup you buy from someone else is that they have set it up and not yourself. Even a 1TB drive cannot fit everything on it, especially if it includes newer systems, and you can't guarantee they have only included one version of each game and not every clone or regional variation.

The big advantage of spending time building a setup yourself is personal preference. You can cherry pick just the games and systems you want, and the versions of each.