OK, for your type and place of riding you feel you don't need a disk cover, Mag racer. Understood.
Brake disks are very strong in one plane and flimsy in the other. Anything one can do to keep side loads off of it is worth doing if one rides fairly harsh offroad conditions with logs, stumps, rocks, limbs, vines, etc. Even on good clean trails an off-trail excursion can put the disk into something that will side load and bend the thing. A small tree wedged between the fork and the disk is all it takes to whack it out of round.
As to questioning the strength of Kevin's carbon parts, obviously you haven't had the stuff in your hands or on your bike. They are amazingly tough, independent of their light weight, plus they are extremely light weight to boot. Aesthetics are a matter of taste and I find them almost works of art. Kevin comes from a family of inventors/engineers/entrepreneurs that holds many patents dating back several generations. Ever hear of Pro Flex (now K2) bicycles? His brother and a partner designed the bikes, built the business, and sold to K2. The E-Line carbon accessories are quite reasonably priced considering the engineering and manufacturing behind them, not to mention the cost of running a business with such a limited market compared to sneakers or golf clubs.
The suggestion that the front disk guard is a frivolous accessory may be your opinion, but a rather uninformed one in MY opinion. The original post asked for disc guard suggestions as in what to get, not whether or not he needed one.