Finding the surface area is helpful in the real world by, um, I don't really know. Gift wrap? With that you should be using
more than just the surface area. Um, what about paint? You could just paint it, but maybe for large objects you want to know how much paint you need?
I'm just rambling so it looks like I have a lot written. This may not be very useful. Being able to find surface area is an important
skill you need to have.
Finding volume, in my opinion, is much more helpful and has many more real-world applications. For example, you may want to know the volume of your backpack to see how much it can hold. Maybe you want to know the volume of your water bottle. Maybe you want to know the volume of a fish tank. The point is, volume is much more useful than surface area. In my opinion.