The C's took the Bucks to OT last year on the road in a game where they literally sat every starter while MIL played everyone, and then in the last regular season meeting between the two the C's put up a fairly easy 140. Even in the 1st round against Miami, the Bucks couldn't stop Butler and the Heat were able to just put up points easily.
So yeah, while Lillard > Holiday, I think the Bucks did get worse defensively so it might not matter as much even if Lillard offers a little more in scoring. And I think Holiday is underrated in clutch moments, the Bucks don't win the 2021 title without him + Middleton especially during that ECF where Giannis missed games. And even last year, it felt like he and Lopez were making all the clutch plays in the stretches where Giannis didn't play