US corporations are also banking at least 2-3 trillion dollars offshore precisely because of high taxes on those profits were they returned or repatriated to the US. Lower corporate rates would remove on returning these profits and thereby greatly boost tax receipts to the Treasury.
For the bottom bracket, the tax rate is raised from 10% to 12% and the standard deduction increase is mostly offset by the loss of the personal deduction. At this level mostly just rearranging chairs.
Nothing says he can’t do this again and again. I think too, he should have started with 15%. Starting with 20% says he’ll probably end up with 25%.