Yes, i wasn't trying to blame spamcop at all. It is of course googles fault and the people that use gmail, and of course spammers, but thats another topic...
We do block the mail (i assume you mean best practices would be to simply tag it as spam) because users do not ever want to see any spam period. not in a spam folder, not in the trash, not anywhere!
block too much, people complain. Block not enough, people complain even louder!
It is the lesser of two evils. Just one of the psychological battles that I fight daily. The users have spoken oh so many times. They would rather miss an important email, then have to click and delete one spam message a day. I've tried it both ways and I cannot win.