Because you did it. I suppose we can take “I just wanted to” to help us distinguish this sentence from the others that you may have given us where you were actually forced to remind us, or say to us or tell us something. “I just wanted to let you know that…. your hair is on fire.” Thanks for taking that extra time and using up those extra words that I got to read so that I could eliminate any confusion about the origins of your intent to inform. You might’ve just said, “Your hair is on fire”, and saved us all a lot of extra bandwidth.

I think it has to do with respecting your audience. As in, when we do this useless posturing, we think it is more respectful than just making the statement. Where did we get screwed up? It is much more respectful to just say whatever it is and not waste everyone’s cycles trying to get to it. SO, don’t ask someone if the sky is blue if you want to know what the weather is like. Ask what the weather is like! Don’t ask, “Are you free tomorrow night?”. Ask the person directly if they want to go ice fishing tomorrow after work.