I don't think this is surprising either. The whole "trickle-down economics" arguments for such tax cuts have always sounded... bullshit (for lack of a better word), exacerbated by the fact that decades of it (since the Reagan era in the US, for example) has only served to make the rich richer, poor poorer and erode the middle class completely. If it was a brilliant idea (i.e. the idea that the the only thing holding back the rich from elevating everyone else from poverty were those pesky low 10s of percent taxes) that worked, everyone would've been favor of it and we would've eliminated taxes for the rich completely by now.
It's always good to have scientific data and analysis confirm your intuition, though.
The poor are not getting poorer and the middle class is becoming rich. In the US anyway. Fundamentally the problem is that people think that someone having more money than then is some kind of ethical issue. Not to mention something like 100% of these analyses are univariate and that makes no sense at all since it's perfectly rational that a 20 year old has much less wealth and income than a 60 year old with an advanced degree and 40 years of work experience.
We could just as easily be outraged that some people have more life expectancy than other people. Seems unfair that a person who is 60 and has 15-20 years of life left has to work 40 hours per week to maintain their lifestyle which is exactly the same amount of hours a 20 year-old who has 55-70 years remaining expects to work in a week.
Citations? (I recall reading an article claiming this is what happened to the middle class about a decade ago, but I don't remember where or how trustworthy. It's hard to reconcile with the real lack of increase in real wages.)
It's always good to have scientific data and analysis confirm your intuition, though.