Making them take the hit as a current expense would eliminate their utility for these companies by making them too expensive. They would, instead, just pay people more (probably...maybe not).
At no fewer than 3 of my previous companies, I've been the recipient of stock options. And I'm about to pick some up at my current company.
My opinion of 'em? They're not worth the paper they're printed on. How much do I have to show for 'em? Exactly zero dollars and zero cents. Therefore, give me more salary. I'm no longer motivated by the stock option racket. I used to be. But that system, as far as I'm concerned, is bunk.
I don't see how companies can get a quantifiable tax benefit from giving stock options to employees yet not have it count against income. Doesn't make sense to me.