Well the dextrose or sugar will not add more malt flavor. In Imperial IPA's it is important to attenuate the beer high. and have a low final gravity. This makes a dry finish..which is important in the style. Did you brew this all grain or extract? If all grain I like to mash at 149 and than skip adding sugar..however with malt extract your final gravity would be high..but if you are extract im surprised you hit your gravity with out the sugar..long answer but in the end it will not hurt one bit and will make a nice beer. Next time use a bit less malt extract and add the sugar to keep your gravity low.
Hope that helps.
Primary: DFH 60 IPA
Secondaty: Blond Ale, Apfelwine, Crandaddy mead
Bottle: Blue moon clone,Kolsch, Eds House Ale, Barley wine, Stone IPA, Oatmeal stout, Hefe,
Drinking: 60 minute IPA, Honkers Ale, Wheat, cherry wheat, Appfelwine,
On Deck: Imperial Stout,