...because they're okay jeans. As other reviewers have said; they don't have crazy stitching everywhere, they looks pretty discreet minus the bulge on the knees, they're comfy, and they stop the wind*.
However, the biggest problem I have with them is the armour on the knees. It doesn't sit, no matter how much you twist and turn it, on your knees when you ride. Instead it tucks on the inside next to the tank. So if you were to come off it'd offer no protection from the road and subsequent impact/abrasion.
Also sizing. I find them to be a little larger in all dimensions than usual jeans, but they're a hard thing to size. I don't own a single pair that're the same size as another. This isn't a problem anyhow because you can wear a thermal layer underneath without restriction or discomfort. And they fit over boots better (Get under your feet in normal shoes though).
Colour.. I actually ordered them because someone said blue-black. Mine are black-black, which I'm not such a fan of but that's personal taste. Can't mark them down for me being vain. The first picture is not a true representation of the colour.
3 stars may seem a little harsh but at the end of the day they don't really protect you from anything but the bike falling onto your leg. But this makes the Kevlar the only real safety feature worth mentioning, and since I've not come off in them I couldn't judge how well this works.
*When they're in front of your knees.