In what way are we the worst ? Honest and open question, no s**t meant.
In all honesty?? Fans of anything in general can be quite obnoxious, if we separate the "fans" from the "fanatics" (which semantically speaking, is the same); many fans connect to a particular aspect or something in such an extremely zealous way, that take that aspect as an absolute representation of the object of their adoration, and many times even refusing the evolution or movement of said object in any way away from the original adored aspect.
Think of music fans that not only reject, but angrily accuse musicians of "selling out" or being "traitors" when they decide to move in any direction that is not exactly the same as the album the fans first got into; as it happens, these kind of fans are the ones who don't want the artist to grow or evolve, simply because they can't do it themselves.
In other, shorter words, plenty of Superman fans are enamored with one particular (and many times as seen here, superficial) aspect of Superman (more than likely one they perceived in their childhood), and won't accept anything that slightly differs from that, and even if a writer/artist/creator/etc, even someone who might have been lauded by these fans in the past, does anything new with the character that differs from their own mental picture of what the character
should be, by virtue of being different to what they want, the artist will be "wrong", while they're "right".
Of course you can find - and certainly do - these sort of individuals in any and every fandom, but at least judging from what you see in this environment (i.e. the internet), plenty of Superman fans are the most inflexible and unforgiving when it comes to interpretations of the character, even when they themselves more than likely wouldn't agree on what the "real" Superman is.
Basically, Superman fans are the reason why he can't evolve as a character.
And I say this as a HUGE Superman fan.