Wikpedia states that web2.0-style site are harder to write.
No. It is hard to write web1.5 applications. Thouse who mix both old html→server→html and new concepts.
What is ‘new’ concept? It is html↔server, you know.
With web2.0 you put whole UI into client-side. Instead of spreading it over client and server.
Just write this UI in static html+css+js and make server-side interfaces for it.