The tax bill also eliminates "exemptions", which were formerly $4050 per person, so the total deductible amount is not doubling. A married couple with two kids formerly could take a $12700 standard deduction and 4 exemptions @ $4050, for a total deduction of $28900. So in 2018 their total deductible amount is going down by $4900.
This effect is offset by a doubling of the child tax credit from $1000 to $2000, and some reduction in rates.
Two years ago I got $7k back at tax season.
Last year, with the same withholding, I paid $500 and made less in income.
People on the very bottom got more back and businesses at the top got more back. I got one hell of a tax hike.