DM Link if you want more detail:
www.dailymail.co.uk/news/article-2359972/Is-fair-dont-Organ-donors-jump-transplant-waiting-list-NHS-plans-boost-donation-levels.html
I can't see why anyone would argue against this. I do think an exception would have to be made for people that can't be donors due to medical reasons. Apart from that, why on earth not?