Weight loss.

The OP mentioned early in this thread about vacuum bagging parts, which has advantages, but it's not mainly strength, its more weight savings as it optimizes epoxy to fiber ratios. making for a lighter part without sacrificing strength much.
Additionally, on structural or semi structural components, and the bumper brackets are the only item on this thread that seems to apply, a few layers of Kevlar properly included would prevent your bumper from departing and/or being run over in a minor shunt, and I consider that a big plus.

Me personally, I would not run pure CF on any bumpers on a street car, but then I live in Florida, and CF offers nearly zero collision protection.
CF IMO is a wonder material, and nobody should be afraid to utilize it. I've worked with FG for 50 years, and for past 15? I have shifted almost exclusively to CF, and have never looked back.
Somewhere else on this site I posted pics of my recent 62 Lancer CF hood and Trunk remakes.