What's so bad about Morpheus in Book 1: he's just the god of sleep and dreams. Sounds pretty chill, right? Wrong.
In Faerie Land, sleeping and inactivity are rarely good things since they are typically associated with being morally questionable. Morpheus doesn't seem to feel bad at all about concocting false and disturbing dreams for Redcrosse, dreams that have a direct impact on the choices Redcrosse makes when he wakes up. Therefore, even though Morpheus lives in a mystical cave that seems far removed from reality, his dreams can have a very real effect.