The Society makes such a big deal about the scripture in Acts that says "abstain from blood" but that very same passage also says "abstain from things strangled", and apparently this is of no concern at all to the Society.
I haven't studied JW history as well as many people here have, but this is my take on why this might be the case. Please feel free to correct me if my facts are wrong.
The Rutherford Era was about picking up the pieces of the movement Russell had started and molding it into something new, something Rutherford could control. Thus a lot of fringe teachings began to emerge (the ban on holidays, Jesus died on a torture stake, not a cross, etc.). Rutherford sought to put his unique stamp on the religious movement. One of the new teachings introduced was the ban on blood transfusions. In the years and decades after Rutherford died, new leaders emerged. They were more concerned with the growth of the religion. They backpedaled and softened their stance on as many fringe beliefs as possible (vaccinations, organ transplants, etc.). They were in a quandary over many of the fringe teachings that had become too deeply associated with the religion; chief among them was the ban on blood transfusions. On one hand, if you do away with it, an obstacle that prevents many people from becoming members disappears. On the other hand, you don't want to cause a stir with the members you already have. JW membership has been lulled to sleep by JW teachings. They don't think for themselves. If you shake them too hard, many might wake up and begin to reassess their faith. Getting rid of the ban on blood transfusions would create a huge stir among the rank and file. It would be similar to the 1975 debacle. The Society doesn't want to risk that, so they've come up with an alternate solution: they're going to chip away at the blood ban little by little. With progressive changes in the teaching, most JWs won't realize anything has changed. Therefore, they're not interested in looking at new ways to toughen their stand on the blood issue. Concerns about blood in meat or strangled animals are dismissed. They'd dump the teaching if they could. However, they're more interested in softening their stance on blood as much as possible without having to get rid of the doctrine altogether. They don't do away with the blood ban because they are married to the doctrine. If they strip it away, one of the major teachings associated with JWs will be gone. Plus, the change would probably upset enough people to create a noticeable decline in membership.
It's something like Roe v. Wade in the United States. Abortion opponents want to get rid of it, but the Supreme Court would get itself into a bind if they overrule it. The pro-life movement would be invigorated (having a palpable effect on the political landscape), and people would further lose faith in the legitimacy of the court. How do you get around that? Simple. You begin to chip away at abortion rights little by little. That's the strategy that most pro-life groups are now adopting as opposed to seeking an outright reversal of the Roe decision. After a while, abortions become so restricted that fewer and fewer women have access to them. In essence, you are able to restrict abortion access without having all of the negative side effects of an outright reversal of such a monumental case. In my opinion, the society is striving as hard as possible to make the blood ban a non-issue. They're slowly allowing their membership to utilize more procedures than ever before. It's gotten to the point that the teaching on "conscience" decisions is so confusing that virtually no one can make sense of it anymore. Most JWs either choose to accept all "conscience" procedures or to reject all of them. I wouldn't count on the Society seeking new ways to broaden the blood ban.
