14-inch mattresses are on the thicker side, which means they offer all the benefits of a thick mattress. Thicker mattresses are much more supportive than their thinner cousins because their internal support structures are often several inches taller. This can be hugely helpful to heavier sleepers and sleepers with back pain who need extra support.
Thicker mattresses also tend to have deeper comfort layers. This translates into superior pressure relief for those who need it. If you find yourself waking up with pain in your pressure points, you might need a thicker mattress, especially if you already have a sufficiently soft mattress.
Finally, thicker mattresses can also help with your bed's profile. Those with mobility issues can especially benefit from a bed that is tall enough to make getting in and out comfortable. However, if you have a low-profile bed frame, a mattress of regular thickness might leave your bed too short. If you don't want to get rid of your existing bed frame, a deeper mattress might just be the way to go.