A Question About Speculars

I have my own (stuck-in-the-mud) views on specular and subscribe to the Microsoft SDK way. There's a good explanation about specular reflection on Wikipeda and another good one hereIn my life I learned that the specular reflection cast by and object depends on the colour of the light falling on the object. The trouble is, I see so many other free and pay mode ls where the dev has made a sepia tone specular texture for his aircraft. The MS way (and, in my understanding - the correct way) is to take the diffuse texture, rotate the colour 180° (i.e. make a negative) and reduce saturation / increase lightness. So when you play around with the HSB - rotation angle, saturation and brightness model you can also create interesting effects such as the preudo-chromalusion effect.The diffuse reflection is dependant on the surface of the coloured material, i.e. the coat of paint - in real lif this is rarely perfectly smooth, even on a glossy surface. The more you varnish and polish a surface, the more reflection you get. A mountaint reflected in a crystal clear lake looks more intense than if the lake is iced over... The rougher a surface is, well then the the reflections turn matt. Diffuse. So the diffuse map and alpha define the reflectivity of a surface while the speculars give the depth of polish and gloss and the way the colours look under different light. (sunrise, noon, sunset)Computer graphics don't reflect light the same as real world and we painters don't have the computing power of Industrial Light an Magic, so we have to "cheat" the specular effect. Like I say - I know and use several methods for my speculars - but never sepia-tone or grey-scales because for my paints they simply do nothing. Technically each single livery needs its own colour specular texture to reflect the colours of that particular livery.So why do other painters make their own monotone spec? Is it just to save the effort of making a new spec for each model? Or is there a sound reason? What can I learn here please? Is there a reason for it?