We have tried to make the Camel Exchange and Message map very closely to JBI in particular but also CXF, HTTP, JMS, Mail, XMPP and most other integration abstractions. We want to prevent leaky abstractions, so the Camel API exposes the underlying APIs so that a Processor can make use of the underlying abstractions if they make sense.
You can probably see a pattern forming now .
For many routing and mediation components and Processor objects, you maybe don't care about the underlying transport and can instead stick to the abstract Camel API. But if you need to, the real transport APIs are there for you.