Well some vendors do. Please read the following quote copied from the press release of Tridion v5.3:
Modular Templating truly separates the design, code and applications of templates into template building blocks. Together with native integration with market-leading design and development tools, (including Adobe Dreamweaver and Microsoft Visual Studio .NET), Modular Templating gives designers, developers and programmers much greater control over each aspect of their template design and code. By combining and reusing template building blocks, Modular Templates can be assembled for a variety of uses.
I’m sorry, are you kidding? I do know over 20 CMS’s with the clear separation in their templates.
This might look like a direct attack on Tridion. Well it isn’t, Tridion is very nice product which is very often ahead of lots of other vendors, but please, don’t sell this kind of bullshit to your customers. Some day they will use it against you…