I'm guilty of this. I feel a noticeable difference when I put some thought into, and actually play with, a lighter touch.
It's so much better when the hand and wrist are relaxed, but it's not an ingrained habit for me yet.
My biggest problem is when I want to play harder with the right hand, and at the same time, keep the fingering light with the left hand. Feels like juggling, something I was never able to do!