Moisturizer's are emollients to protect, and lubricate the skin.
There are many factors as we age that are a primary cause in the skins moisture level to drop which lead to dry skin, wrinkles, brown spots, ect. So many factors of exposure cause this natural phenomenon to happen faster.
In my experience Moisturizer's are important especially depending on the climate in which you live. However, by following a regime of consistent exfoliation you will find this to be as important as Moisturizing. You must remove the old tissue consistently or you will have a build up of old epidermas which will lead to deeper lines, darker age spots, and overall dull dry skin.
As you follow the protocols I have outlined you will see the importance of a balance between Exfoliation, treatments, and moisturizers.