i feel like bells are redundant and inferior to my voice. the tiny lil "ting ting ting" of a bell isn't much compared to me screaming "HEY" in my scariest death metal voice. and my voice is free.
the only time i bought a bell was for the aesthetics of it. it was a fish, and my dad loves fish.... happy birfday pops!
as far as things that should come standard on all bikes... lights, that's the one that jumps out first... maybe pedal cages? i've noticed a lack of foot retention in chicago, which seems like a real bad idea to me when the hipsters are riding brakeless. or maybe they just prefer to stop by sudden impact. i'm not here to judge. i myself have been known to smack into things really hard for no apparent reason.
And shouting is just as or more effective as a bell. Bells are probably fine for getting joggers attention on paths, but in traffic you got to breath in from your gut and project. (David can whistle)