But there are also applications where these HTML-based Master Pages would be essential. They are the servers which have server scripting turned off or don't have it at all, such as mini web servers, possibly done on the hardware router base.
There is one truth about server-based master pages: each time such a page is loaded the client should download the web site design again and again instead of downloading master page once, caching it and then applying to each content page. Such a waste of traffic!
There may be also some profit from Master Pages on client side when saving downloaded web sites to disk.
I think, there already are great drafts for this technology present - no need to invent something new from scratch. Look at ASP.NET Master Pages for example. There are basic elements:
1. Link to master page in the content page
2. Named content placeholders in the master page
3. Named structures with contents, which correspond to named placeholders in master page
Please reply me about your opinions concerning implementation of this feature.
And please remember - I am at least one user who needs this technology :) I had enough time to think about that.