If the purpose of day of silence is to make the community
aware of a homophobia problem, then it doesn't make a lot of sense. If there were a tangible sense of homophobia in the community, awareness wouldn't be the main issue, only prevention.
Day of Silence seems to mean that the people who either are homophobic, or stand by watching others being homophobic, are finally shown what their actions do to members of the gay community. Wearing the shirt and remaining silent shows them, "We can hear you. And it hurts." Unfortunately, the message gets lost because the response sometimes is, "What homophobia problem?" Like JohnBoy said, the reason this is, is that there is no "plight," really. At least at my school, the larger response to the day seemed to be indifference, no one ever thought there was a homophobia issue or at least kept their opinions to themselves.
We're considerably more comfortable talking about sexuality than before, I think, but in many communities there's quite a way to go. Being afraid to come to terms with your sexuality is an issue on the personal level as much as it is an issue when there's a violent consequence of doing so. Being uncertain about your sexuality can cause just as much inner turmoil as "what will my friends think?" If there were a day to encourage not only the prevention of prejudice against those who have a different sexuality, but also openness on the personal and community level to one's own sexuality, it might prove more effective.
-Was that a fart?
-My fault, I fear.