It makes sense to me. We tax companies on the money they make in excess of what they needed to spend to operate, and deciding not to make a donation would have no impact on their income. I would not expect it to be considered an operating expense.

In personal income taxes, I have always seen the deductibility of charitable donations and (in the US) mortgage interest as being a form of social engineering -- donating to charity and home ownership are individual behaviors that the government wants to promote, so it effectively subsidizes them for most people.

Businesses are generally run to maximize profit so you could assume a deduction for charitable giving would be immediately weaponized by creating a charitable arm of the company and donating most profits to yourself, or something equally repulsive.