IMO, the amount of vacation you're actually permitted to take culturally is completely orthogonal to the vacation policy. I've worked in places with a fixed # of vacation days where it was absolutely unacceptable to actually take those days.
If you accrue 15 days a year, work for 3 years, and never take a vacation day, you are paid for 3 weeks and lose 6 weeks of compensation, almost 4% of your pre-tax total over that period (assuming no raise for simplicity).