Mr Raft has an intriguing idea. Everyone is used to casting one positive vote but what if they also had one negative vote to cast? A vote which expresses your attitude towards the person you'd least like to see anywhere near the levers of power.
A candidate's final tally would be their positive votes minus their negative votes, which would deny some of them the smug comfort of their wide majorities. It would make visible those who care enough to cast a vote but whose opinion is that they are all rubbish. At the moment, these voters have little option but to stay away or spoil a ballot slip, neither of which have an electoral effect. Now they have a reason to turn up.
There would be no obligation to cast both votes. You could leave it at who you really, really hate and know that your little vote helps make sure they can't easily get in.
It might be that no candidates end up with a positive tally. A wannabe could get a seat by being the least-hated contender which should stop them comforting themselves that they have 'a majority' or that they 'won' the seat.
Admittedly it would cost more to administer and take longer to count, but it's worth thinking about.