Although I am certain that you meant no disrespect by the question posed - and the answers offered have explained, reasonably well, the “why” which you sought, I am closing the thread for a couple of reasons:
I adhere, strongly, in the moderation of this forum to two precepts enunciated by another forum member (in slightly different circumstances, but which have equal applicability here). I was going to paraphrase his remarks, but decided better of it and searched out the quotes:
[quote=Irish Melkite]It is neither our place as guests here, nor our place as -]Eastern/-] Catholics, to make disparaging comments on the Latin Church’s liturgical forms of worship.
(edited to strike Eastern)
[quote=Irish Melkite]The Novus Ordo Mass is neither less authentic nor holy than the Tridentine Mass; each, as a service of worship directed to God, has its own intrinsic holiness when served faithfully and reverently. To the extent that abuses exist within either, they must needs be addressed; but the form is only that - an external; ultimately, worship comes from within oneself, one’s heart and soul. That said, any valid celebration of the Mass is a recreation of the Last Supper and cannot be other than intrinsically holy, albeit it may be licit or illicit, depending on the cicumstances surrounding its service.
I would posit that the second of Neil’s quoted remarks has equal applicability were one to rephrase the opening sentence to read:
The Novus Ordo and Tridentine Masses are neither less authentic nor holy than the Divine Liturgy, the Holy Qurbono, the Soorp Badarak, the Service of the Divine & Holy Mysteries, or the Holy Raza;
and I suspect that my brother would concur with such a reworking of his sentiments.
I would, btw, close a similar thread directed at Antiochian or ROCOR Orthodox of the Western Rite, asking why - if they chose Orthodoxy, they did not choose it in its Eastern form.
Thanks to all who participated in the thread; it is now closed.