So you're happy with assumed consent, not clear consent?
From what we know:
This woman may not have even realised that organ donation was 'opt out' now.
She may have been fine with donating organs, or she may not have.
She may have been clear with her family, or she may not.
Her family may have been strongly in favour of organ donation, so as she hadn't opted out, they thought it was right to go ahead.
Her family might be looking for some 'good' to come out of her death, but that doesn't mean she discussed wanting to donate organs with them.
She may have told them that she wanted to donate organs, but it seems unlikely she discussed donating her uterus specifically.
It's not likely the case in this situation, but in regards to some people they may not be on good terms with their family despite them being next of kin, so family may not make decisions in accord with the dead person's wishes.
Whatever the case may be, there was no clear, specific consent given to the NHS on the part of the dead woman, only a morass of assumptions.
An opt in system with a list of specific body parts would make much more sense. Or what's next? Someone's family giving permission for their eggs to be harvested, because ovaries are organs and you didn't opt out?