When do you need a WDH

I used my 2720 all last summer without a WDH. After reading about them here and elswhere, I still can't figure out when you should have one. I have Super Springs on my truck, but that just keeps the rear from dropping when the trailer is hitched, as a mater of fact it hardly drops at all. But does not sagging in the rear mean sufficient weight is on the front tires? I just assumed a 1/2 ton pickup would tow the 2720 without any mods. Am I correct? I tow with a 2005 Nissan Titan.