MrPulldown, I made the same observation that you did. If I'm careful enough I can pour straight out of the bottle, but the funnel saves you from having to wipe down the frame when you inevitably slip off the filler neck. And as we probably both know, that's a pain, especially once the oil hits the hot headpipe.
I bought the funnel specifically for my Airhead ( R100/7 ) but tried it on my XR as well and was just pleased as punch to see how well it worked.
In a way this is no different than my EFN tool that makes filling the fuel tank easier on the pumps that have that springloaded boot on the nozzle..
There is always a cheaper/free way to do things but once you get a chance to use the tool you realize how much easier it can be, that's all.