Having everything (presentation, businesslogic + persistence) in one address space or JVM can dramatically smplify the development and maintenance. The problem here: you have to call such an architecture "Fat Client", which can lead to long meetings, inefficient discussions and sometimes even the cancellation of the project etc. Using the name "Smart Client" is also critical: this name is already overused in the AJAX space - so we need something new, cool, but without the "Fat" part.
What about the name W3HI (Web 3.0 Highly Interactive Client)?
Sometimes you should use another name for an old technology - and all problems are gone :-)
NEW: Online Workhop Effective WebApps without Frameworks is also coming to: MUC Airport.