I am, of course, interested in hearing NYer's own response. I may reply to you later.
“It would have been helpful had you included a link or some other documentation to demonstrate that your assertions are, in fact, official Catholic policy.”
This is common knowledge of any reasonably-catechized Catholic.
If you would like a much, much deeper theological explication, you could read Dominus Iesus, written by the former Prefect of the Congregation of the Doctrine of the Faith, Joseph Cardinal Ratzinger, and approved by the late Pope John Paul II.
Here is a link:
http://www.ewtn.com/library/CURIA/CDFUNICI.HTM
If you find the previous document a little longish and a bit of rough sledding, there is an article on Wiki on Dominus Iesus that a quick scan seems to suggest gets some of the main points correct, and is very short:
http://en.wikipedia.org/wiki/Dominus_Iesus
You might also read the Catholic Catechism. Here is a link to an on-line copy:
http://www.scborromeo.org/ccc/ccc_toc.htm
“I am, of course, interested in hearing NYer’s own response.”
Well, of course, NYer can add her own personal thoughts, but if you're looking for the reason why Catholics rejoice when people come into full communion with the Catholic Church, her answer will not be appreciably different from that of any other devout, knowledgeable Catholic.
We desire that all men be saved, and thus, that all come to the fullness of of faith in Christ through His Body, the Catholic Church.
sitetest
Here is a link to the Catechism of the Catholic Church. You can find anything you need to know about Catholicism there.
http://www.scborromeo.org/ccc.htm
Here is another link to a shorter explanation of what Catholics believe.
http://www.catholic.com/library/Pillar.asp