With good frameworks most JSPs are very close to normal HTML and we actually usually have: designers/UX folks who provide PS docs/images/etc..., front end devs (JSP/JS/AJAX impl folks) who take those and make real working JSP pages out of them, and back-end devs who write the Java backing components.
You seem to be expecting these new developers who are just learning HTML to know how to build complex pages using aggregate web service calls via JS, based on a non-standard in-house system.
Even if you don't have separate designers and front-end devs, and I've worked at several places like that, helping HTML designers figure out JSP using a good framework (ATG, JSF) really isn't that bad, it's just a few new tags which are really well documented all over the web.
While I am a Java dev/arch, my "view point" is typically that of a lead architect, team lead, or project lead, so making sure people can get stuff done, regardless of what role they're in is key.
Do you have any live examples of websites built using your proposed method?
Sorry I missed hitting on this one. I do not expect a designer to be doing service calls that is the point. You can write a JavaScript controller that grabs reference to any UI components that it needs, you do not write JavaScript in the HTML, the designer is then working in pure HTML CSS. The JavaScript developer is the one orchestrating the work-flow logic in a code-behind manner. Each person has their domain and once a developer feels comfortable they can graduate to the next domain. Just as I don't expect a HTML designer to have to know Java constructs I don't expect a Objective-C developer to know HTML constructs. It's not about constraining people, it's about re-usability of reusable components and isolating non-reusable components.
As well, I am not proposing anything any more non standard than say JSP or Struts and Tiles. Their are plenty of AJAX frameworks that provide all of the bolts to erect this style of system without building and in-house system. Further, JSP is only standard for web development it does not take into account the variety of UI possibilities and that is the point of the matter. The UI much like the database is only a portion of an overall system. Just as you would not write you data-storage in your logic tier you should not be coupling the UI tier to your business logic.
There are plenty of sites that use this development methodology. Pick almost any mature "Web 2.0" site and they will be somewhere along in this evolution. Google, Amazon, Yahoo et. al.
I apologize in advance for being vague, but I would prefer to not loose my anonymity on this site and referencing my work would do so.