Abstracting from tax considerations, one must assume that the value is the same for the employer irrespective of the nature of the instrument that conveys it--which could be cash or its value equivalent in the form of stock, free rent, a college annuity for one's children, or an option grant.
The ability of options to substitute for cash obviously rests on an expectation by an employee that the price of the company's stock will rise. Expectations of stock price movements, in turn, appear to be significantly influenced by recent stock price behavior.