It's all up to you. In my opinion, yes. It makes a perfect sence. It actually doesn't matter that much where you keep the content (HTML code in your case). It might be important to understand that files are kind of a database too.

For images, you can for example have media library and make it easy from your CMS to paste them to the content as URLs. Another idea is to develop (or use third party) shortcodes system, making image pasting as simple as that:

[img]icons/ok.png[/img]

And as a final thought, if your site is all about displaying content edited by people, consider using existing CMS, like WordPress for example. No need to reinvent the wheel.