you actually gain coins, if someone mine with your profile, because every earning will go to your account
and with a low threshold, you don't even need a password for your whole account...
I like the no passwords I set up miners I sell on ebay so normally I can see a minute or two on my pool which shows buyer got it working right. I don't always do this but it is nice to see.
As far as no password I would always have a account password with dual factor where possible. Just practice good security is a good thing. But as far as worker passwords does not matter at all.
Only way you do not need a single password is when you mine directly to BTC address and BTC address is your username.