Then based on that suggestion we should remove the folder checkbox from the document editing page. I think this is going to lead to a lot more confusing and frustration in the long run. Training a person what the checkbox for folder is/does takes less than 60 seconds.
To use the Windows analogy for folders is also a potentially dangerous road to go down. A web site is not your local filesystem. Windows folders DON’T contain data/content. They are simply hierarchical storage containers devoid of data (ignoring metadata and special circumstances like .app folders in OS X, but typical users don’t know about that stuff anyway).
A MODx "folder" can contain content. So is it a folder, or is it a page?
The more I think about it, the more I’m in favor of getting rid of the folder icon entirely, and just letting the indentation indicate a document heirarchy and structure... like a sitemap. That would make the "is folder" checkbox become "is parent". And with the new skinable manager system in the next release, if you absolutely must have folder icons, you can easily do that with a custom manager theme.