That one was voluntary though. He remembered that there was a Clara and the things he did with her, but nothing about her as a person. Someone didn't do it to him; he chose it.

Donna had all her memories of everything that had happened to her, all her personal growth, taken from her. I assume that's what he was going to do to Bill, though of course on a very much smaller scale. It wouldn't take much from Bill, unlike Donna, but it was still going to be not her choice. I love that she called him on it.

I have a deep loathing for all memory-wipe tropes (and "it was all a dream") and was furious when doing that to the kids in The Dark is Rising series by Susan Cooper ruined all the books for me.

[Edit] Nice layout! Did you create it?