Because we have not seen any real game play. The game play we have seen was dropped frame rate(The enclave helicopter scene), low resolution, practically looks like a mod of fallout 3, etc. Before you say "Graphics are not everything" remember that it's 2015 and fallout 3 and skyrim looked like absolute **** ! This makes people not want to play it no matter how well others think the repetitive 'dynamic' regurgitated fetch quests they generate. Also the world they claim that 'lives' was a simple background process modifier, that levels up all things in game relative to your level and skill. Basically a glorified:
enemyLevel = enemyBaseMod * playerLevel;
Being hyped about something for no reason other than it's an established name is stupid, it allows the developers to ride on their name and not their content. Stop allowing developers to shortcut though their content.