The problem is with saying about people with less severe disabilities will be losing out, is that PIP is not about the condition but about how the person is affected.
So you might have someone with heart failure for example, my dad had that and atrial fibrillation, they can be weak and tired and unable to work much if at all, and can have these episodes of syncope / fainting (but possibly PIP which only looks at how you are the majority of the time, might not look at that, not sure
But anyway, that person might be able to do some of the daily living activities, maybe slowly and with a bit of help, might get some 2 point scores but they would not qualify under the new rules, or be able to work either.
They might lose their LCWRA if that is going too, and losing PIP would not qualify for the health related part of UC as it is not going to be called
But work for this person could worsen their health especially if they have other conditions which a lot of people do get as they get older.