The real problem comes from the fact that any amount of stock that would generate significant return becomes prohibitively expensive to exercise. If you're granted 100k shares at $5/share, and they could eventually sell at $15/share; it does you very little good, because there's no way you can swing the half a million bucks it'll take to exercise in order to make your uncertain $1M profit.

On the other hand, if it's an amount of options you can afford to exercise (e.g. 1k shares @ $5 = $5k… most people could scrap together the funds for that.), your profit is unlikely to be more that 2-5x, which likely would return $10k, and at the most $25k on your $5k investment. A lot of risk and trouble to go through for very little gain…

That said, with a 7+ year time period to exercise after leaving the company, it's not an issue