Saying "Holy Ghost" instead of "Holy Spirit" is a shibboleth of sorts, a keyword that shows we are Traditional.
So it is good to use "Holy Ghost", to show we are not ashamed of Catholic Tradition.
Also, all the Modernists use Holy Spirit. That doesn't mean it's objectively wrong, inaccurate, or sinful -- but we shouldn't use it because who wants to sound like a Novus Ordo Modernist?
In other words, we should avoid the term "Holy Spirit" for reasons of PRUDENCE and that is the end of the list. There is nothing objectively wrong with the term.
It is also a bad idea to bring the Gospel, or our speech to God, down to a comic book, banal, everyday tone or level. That is why we shouldn't call God with the same term we use for the mailman ("you").
There is a similar reason for women wearing long skirts. (There are other reasons too, but I'm focusing on just one reason here.) Even if one could argue that certain kinds of pants with a long shirt over it met the norms of Catholic modesty, why would you? I mean, most worldlings aren't going to single you out or give you a hard time for wearing loose fitting pants with a loose shirt over it. Won't they just assume you're like everyone else in the World? How will they know you're a Trad then? Why shouldn't we scream to the world that we're Traditional Catholics, and that we're not ashamed of our Faith?
You don't want pagan residents of Sodom and Gomorrah to treat you like one of their own, or fail to give you a hard time, do you? You really want to "fit in", in the modern day Sodom and Gomorrah? God forbid!
You really want this?
I love Hillary Clinton! She is awesome!
Obama is like a messiah!
Archbishop Lefebvre was a disobedient rebel!
The Catholic Church is horrible!
Abortion is just reproductive rights for women.
People should be able to love whoever they want.
Matthew is a great guy!