Exterior paint is not just for curb appeal it is also for protection from the elements. In Texas we have intense heat and it is very hard on exterior surfaces. We also have rain and lots of it so between the wet and the heat exterior wood will expand and contract causing old caulking to crack, which will lead to moisture getting inside the wood, and eventually causing water damage to the structure. Now you not only have to paint but you end up replacing wood that has been damaged so you always want to protect the outside of your property by maintaining the paint job on the exterior of your home.