This particular example is probably a bad illustration, with all the recent rage about PII and privacy. In some cases (such as this) you want to make sure data doesn't leak all over the place and anything accessing it follows a strict path.

Anybody modifying Customer object would hopefully be in the right mindset regarding personal information, but once it gets out as a string from GetName or GetEmail, all bets are off, it gets into all kind of logs.

Anything security related is the same.