Wouldn this encourage people to send spams promoting sites that pay for clickthroughs?
If there are still sites that pay for clickthroughs, they must already have some way to protect themselves against people who generate traffic by spamming. So there would be no money in it. This is a bad idea because it just uses up more bandwidth. That’s like arguing that we shouldn’t have police, because in addition to all the losses caused by crime, we have people taken away from productive work to chase criminals. If FFBs make working unsubscribe links universal, the result is net less use of bandwidth. I’m not proposing that FFBs should be used by people on dialup lines, just by users who have bandwidth to spare– people at universities and corporations, and on DSL lines.