I just rolled my eyes at that headline and didn't even bother to read it.
A sandbox simulation?? I don't think very many people want that. A proper sandbox game would be a game with NO quest scripting at all. It might have goals, but getting to those goals would be entirely on you: no scripted wizard to educate you on the magic system then getting killed so you can go on and be the hero, no scripted betrayal by a loved companion. The game might have wizards partial to training young hero types and it could have a loyalty and hidden motive systems for people that choose to follow you, but nothing pre-set. Kenshi would be an example of that.
They sound awesome and, if you like that kind of thing, they have insane replay potential. The stories aren't nearly as good as stories written by skilled writers, though. Also, a lot of people (most?) really don't want to mess with the whole "discovering what is fun for you" thing. They come with a lot of "discovering what is not fun for you" time, after all.
A game could always give sandbox'y side activities, I suppose. Breeding & racing chocobos in Final Fantasy 7, for instance, or playing the game for extra long so you can fight optional bosses. I don't remember anything like that in any Bethesda game, though.