To each their own. If you use you're phone a certain way, and you don't want to change the way you use it, then by all means use a task killer. It doesn't change the fact that if you are willing to take the necessary steps, they are not needed, and in fact, can make lag and battery life worse. I think we would all agree the Cyanogen and Koushik are two of the most knowledgeable people in the android community if not THE most. Both of which say task killers aren't needed. Argue with me all you wish, but I'm not arguing with them.
And I should note that this comment isn't directed at you G.Armour