Why we shouldn't make [destination] optional

As much as I would like to make as many properties optional as possible,
I don't think that this will work for [destination].

If [destination] is optional, then we have to define behavior for when
it is missing.  Unless I've missed something, that behavior will be
exactly what we're currently defining for anonymous [destination].  But
since anonymous is available anyway, there will be no real difference
between leaving out [destination] and using anonymous.  If leaving out
destination means the same as giving anonymous for [destination], then
anonymous is effectively the default value, and we might as well just
say that.

In other words yes, the two approaches (default to anonymous and make
optional) are equivalent, but given the structure already in place,
defaulting is clearer.

I'm pretty sure someone made essentially this argument on the telecon. 
If so, +1.

If leaving out [destination] does /not/ have the same effect as making
[destination] anonymous, we need to be clear on the difference and the
reasons behind it.

If we want to consider making [destination] optional anyway, it would be
option 3 on the list of choices for CR 20 [1].

[1]
http://lists.w3.org/Archives/Public/public-ws-addressing/2006Feb/0058.html