I see you have 506.382 SP. Once an account hits 500 SP it gets this "ability". To me it's one of the most useful parts of the curation system. I like it. But you're right, there should be a setting to allow for "always vote at 100%". Then you'd never need to click twice.
But one thing useful about this ability is the 1% option. I do that when I want to say "I agree" or "this makes sense", without having to use up much voting juice. You can only vote 10 times a day, max, without depleting your juice to nothing. So gotta make use of those 10... sometimes I vote 8 at full power, and split the other 20% of my juice up into smaller votes, including some 1% votes. It can be handy.