The changes from the 1962 Missal were simply to put the ICEL stamp on the Creed and get the use of "we" in there (yes, I know the difference between the Nicene and other Creeds, but the fact remains that it was CREDO in Latin). The ultimate objective of the ICEL was probably that of making significant changes to the text; I recall reading its next objective was going to be a "gender neutral" version, although I don't know how true this was.
ICEL "translations" of anything were noted for being agenda-heavy paraphrases. They were much more "creative" than any other of the European language translations, for example. And the ICEL only got reined in very recently.
Heavy handed clericalism, and like that of Archbishop Cranmer, with a theological agenda at variance with tradition.
The first changes ALSO had the benefit of giving ICEL copyright-revenues--a LOT of revenues.
"the fact remains that it was CREDO in Latin" -- let me ask you this, then. It IS credo, is it not? When did 'WE believe' start? Isn't it part of the Vat II shenanigans? Like holding hands at the Our Father? It smells like that ....