It is Urahara's deep fascination with humans – breathing, living, not not Dead – that leads to his disenchantment with Soul Society. With the system, with the attitude, with the King.
Humans are weaker than Dead. Fact.
Humans knows less secrets than Dead. Fact.
Humans appreciates life less than Dead. Fact.
Humans are – in every way that should really count – worth less than Dead.
But still. Still.
Humans are so very defiant. So very, very stubborn in their insistence to be more, that they can't help but continuously beat the walls framing their existence.
Always thinking, asking questions, not just mindlessly settling.
There was a Box, but then there wasn't.
Humans are so much more Alive than Dead.
Fact.