You are right, small investment cant make a decent profit, but for some people who never invest will be happy if they can try to invest with small amount. The point here is "to try" before they go for bigger investment.
I think that any amount of BTC is valuable.
Yes i agree, you will not earn much but its better to put here 0.005 rather a hyip/doubler/scam from the start site and as dustboy said, the point is to try...
And then why you are not saving it more before you can start to invest? You are really wasting time if you are investing that small amount. Lets say you invest in a month and I can guarantee that your profit dont even worth a penny. And why you even try it when it does not worth?