Why does Ophelia rouse the pity of the audience?

I think that an appropriate starting point would be why
wouldn't she be pitied.  She is the one character in the drama that no one could really
fault.  There is little way one can blame her for all that she has endured and all that
she was forced to endure.  She is pitted between the scheming of her father and the
irrationality of Hamlet.  Her father, who should be validating her own experience and
her own predicament, ends up treating her as a means to an end, as opposed to an end in
ofitself.  At the same time, she must endure Hamlet's treatment.  If there is question
about Hamlet's cruelty, it is confirmed when the reader examines how he treats Ophelia. 
The idea of not only denying his love for her, but also suggesting that she was crazy to
believe so is part of his cruelty.  At the same time, Ophelia's voice is never really
validated and authenticated by anyone.  Her madness and eventual suicide is a critical
point in that it reflects the danger of silencing voices.  It is for this reason that
Ophelia arouses pity in the audience.  One can only feel a certain hollowness or
emptiness at recognizing Ophelia's pathetic state.