Straight HTML has a lot disadvantages. It requires extra code for index creation and search functions, must be opened in a browser, and is a lot slower and more space-consuming than CHM.

This is the reason why almost all software packages, including ours, have abandoned HTML-based help files some years ago, and switched to CHM. I'm afraid we won't go back. If you want to edit the file you can relatively easily decompile and re-compile it.