I think this is more of a reflection of computer literacy.
When my computer does something wrong, I assume its my fault. When my parent's computers do something wrong, they complain at it. Pretty uselessly.
I guess Clippy just makes people who don't normally over-anthropomorphize computers over-anthropomorphize enough to get annoyed.
Well, you often are not doing anything at all wrong when Clippy gets in your face. Its annoying because it reliably fails, until I disable it.
From this 2001 article:
I, at least, found this amusing.