IMO it is definitely worth going up from load range D to E. You get a tire with additional belting. It is a heavier carcass. The construction features that make it capable of higher internal forces (holding higher air pressure), gives it greater resistance to outside forces as well, such as hitting potholes and curbs.
Just remember, you have not increased the GVWR of your trailer. You're still limited by the axles, wheels, suspension, and frame. What you have done is increase the safety margin of the tire capacity. It does not cost very much extra per tire, and is money well spent. Use your existing wheels.