Because the economic environment doesn't support it.
First, if you cut taxes, you have to reduce spending.
Second, you have to make it possible for people to work in the US in competition with other markets.
If you owned a business that made widgets, because of all the taxes and regulations in this country, it would cost you $1 to make a widget. Lets say that because of competition, you can't sell it for more than $1.20.
Now move the manufacturing offshore. In China, they can make the widget for $0.20. and then you can import it into the US and pay $0.30. now you have $.50 invested and still can sell it for $1.20. Any reasonable person would do that.
Well to change that, you have to make it cheaper in the US or make it more expensive from OffShore. Either you lower regulation and Taxes here or you Tariff it from there. Which do you choose?