I would agree, I also prefer when users attach images than hotlink to third party image hosting services, for the reasons you stated and also because many of those images stored on such sites don't render at all in some OS/browser combinations.

I don't mean this to be harsh though, but I don't feel your initial post qualifies as an article, but rather an opinion. To me, an article should be a detailed explanation on how to do something. :)

So should i edit it and add a detailed explanation on how to attach images?

Well, I suspect most users here know how to attach images (it is the users on their forums that would need to be addressed about that), however you might want to research the options admins have to auto-convert hot-linked images to files stored on their servers, perhaps using products already available here, and provide an explanation on how to accomplish this, including the pitfalls, pros/cons of different methods, etc.

Look at the various areas of confusion that might have arisen regarding this issue and provide information that brings more clarity to the options/solutions already available.

In short, you want to take the available information, and bring more clarity to it, and unify presently disparate information into one cohesive article that will be of value to as many vBulletin owners as possible. :) Sounds easy, right? :p