Well, don't forget that the timeline for most forested areas would look more like "forests managed by native peoples -> land clear-cut by European settlers -> u

Well, don't forget that the timeline for most forested areas would look more like "forests managed by native peoples -> land clear-cut by European settlers -> un-managed forests," though I'm sure "un-managed" is debatable here; humans never left. Much of New England was clear-cut, either to harvest old-growth timber or for farmland. The forests we see today date to after the westward expansion, when farmers left the rocky New England soils for easier tilling in the Midwest and Great Plains states. So really, when people want to conserve the land in that state, they're saying "let's let the new-growth forests come back and maybe become old-growth forests again."