In answer to "Why?": Because that would not specifically address Vitalik's point.
I do not believe that infinite access subsidies for the poor is part of EOS's design -- Dan conceded Vitalik's point on this issue, and countered that Ethereum is even worse for the poor.
I don't think he did concede that point. He went on specifically to say that services pay, not users.
Users including the poor will use EOS just like they use Steem where they will have greater barriers to entry on Ethereum and similar models.
Empirically Steem is being used massively in the developing world, including by people who are not wealthy at all. So contrary to Vitalik's claim that they need to purchase stake to use a blockchain built on this model, they don't. Services provide the stake (perhaps through delegation), and users provide value in other ways.