If you consider the brightness of some of the current LED car and truck rear lights, they're about the same as anything I've seen available for motorcycles. Considering this, the rear light on a motorcycle needs to stand out more so it doesn't get lost in all of the other rear lights at night.
If you don't want to be conspicuous, that's just fine. Actions always have consequences attached. We all know the universal excuse for killing a motorcyclist: "I didn't SEE him".
15 BMW RnineT
10 Ducati 1098 Streetfighter S - "Sleipnir"
09 Kaw Versys
67 Triumph Bonneville TT Special