Unless people are happy with what they have, they are constantly demanding updates, new modes and situations.
From the article snippet there - sounds like someone isn't familiar at all with the MMO genre, if that came as a surprise. Which seems like it did since they have to adapt to this response.
Pretty much since AC, regular (free) content updates have been expected by customers. Larger paid expansions to keep retail shelf space are fine and dandy too - but for your monthly fee people will ask a lot.