This has been brought up quite a few times but I, still, really have to disagree that the way Sitefinity handles images is inconvenient. The website templates file structure
shows how custom templates and themes should be constructed. If we follow it, the end result is a very organized and portable package.
To access files inside of your theme, you can use something like this:
If an "Images" folder is required, because of existing code, then this knowledge base article
covers how to change the default behavior.
My point is, like I said a moment ago, the recommended structure
hasn't ever caused me an issue. It's really the way to go. :)