There are plenty of reasons to hate Java, but these aren't them.

Why are you wrapping and unwrapping your objects three times over? Just use hibernate properly and it can replace all those generic DAOs.

Yes, generics aren't available via reflection for backwards compatibility reasons, and this is unfortunate. But the getModelClass() workaround is pretty simple, and you only need it at all because you've overengineered everything.

Yes, traditional java.util.Date is terrible, we know. It can't be replaced because of, again, backwards compatibility. If you're doing serious work in Java you use JodaTime and your life is good again.

Hibernate can manage the client/server communication ? I thought it was just to manage the server/database communication, and we used OpenJPA for that, so it's kind of the same. My DAOs (yes the name isn't exactly the right one, but I tried to simplify) are for the client/server communication, and in my case for the GWT's RPC service implementation. And instead of having a lot of service (on for each screen for example), or a lot of method in one big service, I tried to have only one service. And for the Date, JodaTime is awesome, but again, not compatible for the GWT's client-side. But yes, there is other solutions than the built-in Date.

Hibernate won't do client/server communication (or at least it's not its main focus); given what you've now said, the point is that you don't need more than one "DAO". After all, the implementation code is the same in all cases.