Dungeons and Dragons is not just a game it is a commercial entity. Changing the structure of that entity in such a fashion that it only has passing resemblance to its previous incarnations dilutes the brand.
And sure the argument here can be, "Let the old guys play there old game, this is new D&D for a new era." But who is this game appealing to specifically? What is the long-term viability? How does it relate to the past incarnations of D&D beyond name and familiar concepts (classes, levels, races, etc.)? Is it D&D in name only?