Last Call Comment (Core): Utility of [source endpoint] property not clear

Ref: WS-Addresing 1.0 - Core 
(http://www.w3.org/TR/2005/WD-ws-addr-core-20050331/)

The utility of having the [source endpoint] property from the receiver 
perspective is not clear.
Specifically why does it need to be an endpoint reference?
What useful purpose could it serve to the receiver and why would a 
message sender include that property in message sent?

Section 3.0 last paragraph seems to imply [source endpoint] may serve to 
be the default [reply to] or [fault to] in certain cases:

"Requests whose [reply endpoint], [source endpoint] and/or [fault 
endpoint] use this address MUST provide some out-of-band mechanism for 
delivering replies or faults (e.g. returning the reply on the same 
transport connection). This mechanism may be a simple request/reply 
transport protocol (e.g., HTTP GET or POST)."

But that is explicitly ruled out in other parts of the specification 
that require [reply endpoint]  property.

Why not default the [reply endpoint] and [fault endpoint] to [source 
endpoint] when replies and faults are to be sent to the "sender" of the 
request than a different (or same) endpoint explicitly specified in the 
request.

This is analogous to email From and ReplyTo headers.

If the above is not done the specification needs to minimally add some 
explanation of the intended utility of this property.

Regards, Prasad