Here's an alternate perspective: one of the advantages of a rapid release schedule is that it provides options for us consumers. Maybe some like adventures, while others prefer to roll their own. Some might like lore-filled deep dives into various aspects of settings, while others have no use for that stuff. There are definitely those who would enjoy a book filled with cool magic items, but for others the DMG is enough. From our perspective as customers, this would be good.
But from a business perspective, you're better off maximizing profits with a sparse schedule, and leave people hungry for more. And clearly, a schedule along the lines of 2e is way too fast. But I think that long-term, there may be benefits to a faster and more varied release schedule, because it keeps more different kinds of people interested in the game, and there are likely "tentpole" releases that would sell more in that case.
And I'm not sure the 3e and 4e release schedules were unsustainable. Did they maximize profit? Probably not. But I haven't heard anyone claim they were losing money on them – only that they weren't making enough money for their corporate overlords.