Even if takes 2 minutes to respond to a message, the number of messages is too high. Most people have more than 50 emails a day at work and, I am sure, filter out OK cupid messages. I do not see them in the inbox - I auto-archive them. I get over 50-100 emails at work a day and 10-15 personal emails a day - that is more than enough. I am not even in a people managing position and those folks get more email and more interference. OKC emails, just as Facebook alerts all sort of other stuff that is overflowing there, are a type of interference/interrupt, and people intentionally auto-archive such emails because they are trying to focus (on work, life, whatever), and it is a known fact that in order to focus, you want to avoid interruption. Work email, IM at work, personal email are interrupting enough. So people auto-archive OKC, Facebook, Twitter, Yahoo Groups, and all the rest of that. The basic truth is that OKC messages are one type of information, and we live in the world of too much information, so there is competition for the attention of a person who is in the sea of information, and that is tough. Basically, OP is competing not just with other guys on OKC, but with the girls' facebook friends, etc.

It might not be so pronounced in OP's age bracket, but once you get to past college years, that is basically what it is - trying to compete with a lot of other priorities in somebody's life.