The Double U
"@Background Pony #749F":/images/2641574#comment_9691728
They are useless, but Probably Not as dumb as The Banana Guards.
Also, it's because it would make them look cooler, and more protected in a Fight. If I were in Charge of G5's Story, I would try and Improve The Royal Guards a little. Heck, in My AU Story for MLP, both Celestia and Luna's Guards have Helmets that protect their Face (in a Beaked shape like Nightmare Moon's Guards in Season 5's Final
e,) and (I guess Now,) have full body armor.