Of course, the reason why there are so many deductions and credits in the income tax is political (and bipartisan). If a politician wants to subsidize something, putting it in as a tax deduction or credit makes it far more permanent in a political sense than if it were a spending item in the budget. Spending items are easily targeted for cuts as “wasteful government spending”, while removal of tax deductions or credits are criticized as “raising taxes”.
As you are filling in your IRS Form 1040, think of all of the embedded politics in each line.