Veggies is not the direct cause of dry skin on the legs as per say but it is indicative of someone who does not get hydrated and nutrients enough. Veggies contain lots of moisture and nutrients too that is vital not just for proper digestion and growth but it also effect you in ways that is exhibited on the exterior of your body like your skin. And skin thorough out your body are not the same even if you don't see any join marks and patches but differences are there visible with your normal eyes and at times under a microscope or just by touching it. One of the key nutrient you need for good skin is Vitamin A and well this is found in abundants in .....yup veggies and fruits.
Dry skin is not lack of moisture but the delivery system could also be less efficient for a number of reasons and aging for example is one good example. Look at a elderly person and you see more smooth dry crack skins. It can starts on the skin in your lower limbs but as you age..it started to appear in other limbs and face and then the body.
So you can improve it abit by taking supplements like vitamin A capsurel..etc but there are also nad side effects to that. Soe supplements are not absorb well by taking them in this way. And in the case of Vit A...just enough of it is great for you but too much can cause toxicity. So by dieting on veggies and fruit...the quantity you normally would eat daily is the best way and naturally.