Cirkeline said,
"They have to make blood transfutions legal veeery slow and over a long time to prevent too many legal cases."
I believe you are right about that. The Society seems to be in a state of transition over the blood issue. It's already ok to take many blood components that were banned in the past, and in 60 or 70 years the whole blood issue will likely be dead, just like the ban on vaccination. Stemming the flow of lawsuits is probably the reason for taking small, incremental steps forward.
Watchtower has been so clever at controling information that most Witnesses are not aware of the Society's past views on medical issues. These days though, with the proliferation of the internet and electronic media, making information readily available, the organization will have a much tougher time controlling what people know. The Society's ban on blood transfusion will not be forgotten as easily as other issues from the past.