Ask Foghorn: Are Lasers Really Useful?

Reader Joshua asks (nearly a year ago now):

Can you tell me how useful a Crimson Trace laser system would be for a beginner?

A red laser sounds pretty cool. Green laser sounds cool too, but given physics, is going to have more powerplant issues, and buying batteries is annoying, and replacing them often is annoying. The whole option itself gets this new shooter wondering: how important is a laser sight at all? Is it a supplement for dark environs? Is it to make things easier in a chaotic combat situation, day or night? How hard are red lasers to see, how easy are green ones? . . .