100 people visit a ride in an hour. That ride is replaced by a new ride that has 1500 people visit it an hour. While space has increased in the park, capacity certainly has. Unused capacity being fixed is what it seems they're going for. Dinoland and Rivers of America aren't pulling the numbers to help fill out their parks and give people more to do. It may not be the whole solution to the capacity issue, but it does help with the capacity issues.
And I disagree on the 'less e-ticket' idea. While I get the sentiment, e-tickets sell tickets. Dumbo isn't selling a ticket. WDW cares about selling tickets. Now, I agree that you have to have both, but look at the response Journey of Water received. Those type of responses certainly aren't helping the argument.
That said, I don't think we need less Dumbo-level rides. We need more, you're correct. But not at the expense of more e-tickets, but in conjunction with them. They cannot move numbers on their own (see JoW), but when combined with other e-tickets, they create atmosphere and don't have to pull weight on their own.