My experience is similar. I'm currently job hunting again, and this week I spent hours reading through this month's "Who's Hiring" post, making my best effort to write cover letters addressing what each company needs and how my skills and experience can assist them.

I got 2 responses. Both were impressed by my resume so I don't believe that's the issue.

Its really hard not to take it personal when it's such a common experience. If someone sends you an email, you reply. It's basic decency.