Why can't a vocaloid have a personality? Does Gregory House have a personality?

Gregory House is the main character of a TV show that has actual plots. Vocaloids are just animesque moeblobs.

Furthermore, Gregory House is not credited for programmatically singing songs actually written and composed by humans.

I think the idea of "Miku" is a stand in for a large group of people, just like "Google" is.

Except people don't treat it that way. In any case, our senses don't work that way. If it's anthropomorphized (pointlessly, in this case), we automatically think of it as having the qualities of a person, whether it makes sense or not.