I'm new to the world of RDF and RDF/XML so pardon my naive question:

I understand that the "real" RDF model is the conceptual network of 
nodes (Subjects and Objects) connected by predicate arcs; and that the 
official way to serialize the graph is to use the RDF/XML specification.

So far so good; but N3 and/or N-Triple notations are also used, and it 
sure seems to me that N3 is  "iso-morphic" to the graph; i.e. The 
triples (properly constructed) represent the graph, the whole graph and 
nothing but the graph.

And now the question:

If we need to express the graph model in an XML -ish form, why wouldnt 
it be easier, simpler, less fattening, whatever, to start with the the 
triples thus:

<tripleSet>
    <triple>
      <subject>http://mydomain.com/myStuff/Thing42.doc</subject>
      <predicate>http://mydomain.com/myvocabulary#title</predicate>
      <object>Sitting On A Fence</object>
    </triple>
    ...
    etc for all the known triples


</tripleSet>

But as far as I can tell, no one has done or proposed such a thing. Has 
it got some sort of fatal flaw, conceptual or practical, that I'm 
looking right past?

What makes RDF/XML , which to my inexperienced eye seems a bit clunky in 
comparison, the preferred notation over N3 or an xml-ized version of N3 ?