I'd be happy to enlighten you. And there is no need for the tax system to be complicated.
Taxing income is how US personal income tax works, albeit with a minor percentage rate increase as income grows. I pay a personal income tax regardless on how much my kids school cost, how much my phone bill is, etc. The Feds and my State don't care how profitable I am as an individual. They bill me on my income. Why should it be different for corps?
As a business, the rate I pay for my paper, utilities, travel, etc is largely independent of how profitable I am. If I print frequently, then 10% of my income might go on printing. Why should taxes be different? Why should the tax structure be biased against profitable companies, but sympathetic to companies that can't make profit (or pay taxes). Why should other tax payers support low profit companies? Why should working class, or indeed any tax payer, subsidize lawyers, advertising, sporting events, the olympics and fancy hotels, or any business activity that a business requires to function? If the business needs lower taxes, reduce the headline rate.
Moreover, a tax system should be fair and equatable. Profit based taxes induce all sorts of undesirable behaviour, from booking business class tickets, as "otherwise it will go in taxes" to cooking the books/system to appear to make no profit (off shoring, Ireland until recently etc.) benefits for firms that can afford good accountants, etc. Please note that this is income tax I am referring to, not a UK style VAT.