I think the vagueness of information during Destiny's early exposure caused players to fill in many of the gaps. Thus creating the hype and many unfulfilled expectations. We knew the game would have Starships and planets and those two things alone can make a person expect many moments of grandeur. Bungie was also touting this as "the biggest game they've ever made". But blinded by excitement, I feel that people read it as "the biggest game ever made". So that made them expect that every planet was a Skyrim. And Marty's music also helped entice the sense of adventuring vast new worlds Add that all together and you have expectations so far out of reach they'd make Peter molyneux proud. But don't fret, I'm sure Destiny will be a good game all the same.