Because as you probably know the UK education system has gone to absolute shambles and this year of Year 11s have had a very lucky escape. The 2017+ students will be the guinea pigs of new Tory ideas and decisions that do not benefit the students. If they can make things harder they will. They can't fix the system so they're breaking it.
Sorry, I'll calm down - but really, I have no idea what their end goal is. Most likely they'll end up admitting it was a terrible idea and the grades etc will change once more.