I don't think ADF is bad, I just don't think it's worth building in. I'll build in ITU/heavy armor/hardened shields instead and pay 10-15 OP during exploration for the option of removing it at a later point, although I probably just don't bring any 7 burn capitals exploring... Odyssey and conquest are plenty good if I need exploration capitals.
When you reach the point of multiple 7 burn capital ships, you're never going to have a great sensor profile (and the changes to phase ships and high res sensors make it a lot easier to compensate), and you really shouldn't be exploring with that fleet, plus 4 tugs gives you more base (non sustained) burn which is a huge upside when fighting remnants IMO. With the new incentive to avoid bloated fleets, 4 fleets slots feels like a much smaller price to pay, and colonies still eliminate any money/resource concerns in the late game, plus gates now make long distance travel cost much less fuel.
Also, late game fights are waaaaaaay harder now, so permanently losing OP for campaign benefits feels like a bad decision to me.