Why can't this be cute forever?

You see this guy? He now weighs about 17 pounds and is just shy of 26 inches long...he's 3 1/2 months old.

Take a close look at the following rolls of chub...and then ask yourself...
A double chin?

How about the wrist hidden in the folds?

Or the dimple thighs?

Why are these things only cute on babies? Why can't they be cute on us adults?