For my casual games I like to make lists and just try different units out. I was putting together a list in my mind of earlier design decisions that just didn't work out and we have clear power creep. Where there are clearly mirrors and or other units that are far superior to the core unit.
Wookie Warriors are my first unit that on paper looks solid but in relation to its mirror and/or other units filling similar roles is way behind. Their heavy weapon upgrade is brutally expensive, their keyword abilities are terrain dependent meaning some maps they could be great and others useless, their guns are range 2 and finally weirdly enough they aren't that scary in melee. Pierce 1 when used against them basically says take all wounds.
Other units filling similar roles: Tauntauns, I shouldn't have to explain why they are superior. Chewie who himself had a point reduction and is cheaper than a full wookie warrior unit and doesn't lose effectiveness as he takes wounds.
Mirror: Imperial Royal Guard are usually much better because of 3 reason. Their heavy weapon costs 10 points less, they can directly counter a jedi with immune to melee pierce and guardian 2 allows them to protect other units in your armies. Generally no matter what terrain or army you are facing they can perform a valuable role.
What units do you have on your lists?