Well, are you asking me as a player or as a GM ?
As a player, I think the GM is what matters, so I practiced games I had little interest in because I trusted the GM, and I’ve never been wrong on that point. The GM’s ability to make something interesting overules the worst games/setting/system/whatever.
As a GM, I prefer classless system but I like them to have rules. I have been a HERO GM for decades for instance. No class there, but rules & bounds aplenty. 😉
What I keep saying is that you don’t need these rules to be *that* defined while the game’s beginning. The GM or Game designer can set them as the need arises.
And so, as I understand it, you don’t want any setting, you want a setting for D&D Next, and nothing else. So, since everything I was talking about was what kind of system you may use and do you need any, at first. It looks like you answered the question. 😉