If you're like most players, then you're not using your entire body to generate spin. That means you're not able to hit a kick serve. That means you're not able to hit a slice serve. And that means your forehand and backhand aren't "heavy."
So if, for example, your kick serve has no "bite," then I want to invite you to pick up a copy of "Spin It!", because inside Dr. Mark Kovacs shows you over 30 drills that allow you to generate spin from your entire body so that your serve, forehand, and backhand have a lot more RPMs.