I don't really see the reason for discussion here. If you don't want it you turn it off. It's the same with Iron Mode, which got implemented just so some people who don't like "save-scumming" can just turn off the option at all. If you don't like it just choose the reasonable option.
That said, I took some time to actually find out about the 100% option and didn't realise from the start that I was playing on 50%. It might be nice to inform newer Players in some way, either by asking on each Character creation or by making the option more prominent in some other way.