7CS: Why are straight draws bad?

[MCS]

Hello,

I am totally new to 7CS. When I say "new," I'm talking "never played it for money." I do play holdem decently, and I have a reasonable understanding of poker theory as well as a very strong mathematics background.

Anyway, my question is: Why are straight draws so bad?

I've read things suggesting that many good players hate them and often won't play for a straight at all. I'm just curious as to the logic. Why are they so dangerous?

Thanks for the help.