I think that there are good people within the JW organization, and i don't think the Governing Body is as evil as other people here make them out to be, but I still think that if you remove all emotion and look strictly from a "net benefit" basis, Witnesses are hurting people more than they're helping due to many of their rules. If those rules are proven to have no basis, then there is reason to speak out against the organization. Ignoring blood, there are other things that have a huge effect that are basically ignored with a "Jehovah will make up for it like he did with Job in the future" type platitudes.
- With so few numbers, it's nearly impossible to find TRULY compatible romantic relationships. Most people within -force- relationships with whoever is around, and many people miss out on them completely. This causes a lot of unhappiness in people's lives. The could still get the "afterlife" happiness in other religions that don't force that rule on their followers. This also applies to true friendships - in retrospect, I probably had ONE that wasn't fully surface, and it was a guy that's out now as well.
- The disfellowshipping rule, based on one scripture that Paul wrote, that goes against the spirit of Jesus' teachings, has caused pain and suffering for innumerable people. It being stretched in relatively recent years to, "anyone who doubts anything the Governing Body says," is a whole different level of control and pressure.
- If life -is- limited, spending so much time going to multiple meetings a week, assemblies, field service, etc. is a huge waste of it.
...and many more things. That's why people are "against" it, above and beyond just living and let living. Any many have emotional reasons, since they're blocked from communicating with beloved family members because of it.