Yeah but I think a lot of people would be like me - particularly the "squeezed middle" of middle earning professionals - if you asked a lot of people who are doing ok (not earning a fortune but not struggling) would they prefer to earn the same amount for half the hours (and all the savings on tax, NI, childcare and transport you'd make) or work the same amount of hours for maybe a quarter more money, you can't assume everyone would go for the extra money, and, again, would that be the sort of society we'd want from a socialist movement?
But equally you'd get lots of low earners who could massively boost their incomes overnight. They could suddenly pay off their debts, have money to spend on things like holidays, cars, activities, clothes - which would put money back into economy. While I do agree some people would take the "easy option" of working less, others would happily work more hours if they saw a big improvement in their quality of life.
Don't get me wrong, I don't like living in our current unequal society and would be interested in any system that could make it a bit fairer - I just don't think UBI is the answer.
I don't think UBI is the answer on it's own, but I think it would go a long way to improve the situation. Lots of other things would need to be addressed first - housing and childcare costs being two major ones, as well as the current school system where people can buy their way into decent schools.