It could happen that a tipsy driver (that's already a bad thing... but common) not seeing a smart at night because the 'ugly' amber colored reflectors were missing could easily merge with the smart. This is also when the smart is just parked. As tough as the smart is for a tiny car...it ain't no H1Hummer.
Furthermore... if it should ever happen, that if a severe accident should ever occur and a sharp insurance adjuster realizes that these pieces were missing within a headlight, that this ommission may open up a can of worms. This is my wimp factor talking, because insurance companies and lawyers can cheerfully blow things out of proportion.
I looked at the reflectors and they are not an issue in my humble opinion.