No. You lose a lot of flexibility that way. Always take pictures in colour mode (and preferably raw mode). That way, you can tweak the levels of each colour channel before converting to grey scale. Monochrome images can look a bit flat when taken on digital cameras. The reason is partly because monochrome films tend not to have flat colour response curves and will emphasise different parts of the spectrum. There is plenty of information about monochrome digital photography, for example
Another advantage of shooting in colour mode is that you can create toned (desaturated) images. Always shoot in colour+raw mode and do your own conversions to monochrome. Never let your camera do it for you.
I'll try to find some more sites. The one that linked to was pretty random.
Another reason why monochrome photography (both film and digital) can look so flat is that it is difficult to avoid looking at colours when composing images. You must ignore colour differences and concentrate on tone (brightness), contrast and, more importantly, texture.
The only advantage for shooting in B&W mode that I can think of is that if your camera has a digital display (rather than a view-finder), you will see a monochrome image before you make the exposure. This would certainly be useful for making a test exposure if you have the time.
Faced with the choice between changing one’s mind and proving that there is no need to do so,
almost everyone gets busy on the proof. -- J.K. Galbraith
Edited by micksharpe (Mon 23-Mar-15 00:25:50)