The majority of high school graduates can probably easily file their taxes, since their income is likely entirely W-2.
This is not simple: https://www.irs.gov/instructions/i1040s8
You could just say something like "multiply the number of dependents entered previously on form 1040 by $2000, enter value on line X" and you'd still have a child tax credit and the vast majority of people who claim it would see no difference other than taking significantly less time to figure out the amount of their child tax credit. By the time you get to the child tax credit line on form 1040 you've already written all your dependents and their social security numbers right at the beginning of form 1040.