BillieBars

Soooo, would someone explain to me why I shouldn’t buy billiebars (the low pro model) bed rack for my yet to be purchased rtt. Why would I buy a rack that’s 15 plus inches high wrecking my mpg and center of gravity even more. I just returned home from ouray/telluride and did the usual trails and and drove from there and back to Louisville. After 2 weeks of off camber and highway/wind driving, the last thing I want is to worsen the truck with a bunch of weight up high and in the slip stream. Are the high racks solely for hanging stuff on or is there another reason I’m missing. Mpg was 18 on the way out and 15 on the way back. Also anyone have any experience with billiebars? Thanks in advance.