Back to your question about standards. It's cool to program in standards because all JEE app servers support it, and there exists tremendous amount of free learning materials out there. Plus it's easy to sell your job skill.
What happens if the standard becomes slow to innovate, and is relatively less productive than other non-standard programming models?
Sure, there are risks to go with non-standards. To me, the backend tier out-lives the life time of the UI-tier in enterpise applications. I would make a clean separation between the UI-tier and the backend to reduce the risk. For now, ZK seems the best UI programning model out there from my experiences. For the future, we'll see.
(I'm not associated with the ZK team, but just a ZK lover.)