I'm aware how RT started out.
But your explanationation for the most part just makes it easier for RocketTheme - not the users.
Gantry 5 doesn't make it easier.Also, members wanted a common way of getting the functionality required and easy of changing between templates.
Did they? I don't remember that. As for changing between templates, that has never been difficult.
And isn't the engine supposed to be Joomla?
Overall, based on your response, I'd say it was better for RocketTheme to have a framework, not the user.