The English - those wonderful people for whom the word "insular" was first invented! - used to go their own way and pronounce
Maria with the -i- making an -eye- sound. I wouldn't say it's "like"
Mariah, because the -h is just there for decoration and has no etymological significance.
However, starting I suspect in the late 19th-early 20th centuries, they started using the, let's say, Continental pronunciation of
Maria. This meant that for a long time the -eye- version sounded old and outdated, so it fell out of use, until the singing
Mariah came along and rejuvenated it. (And a police van is still a Black Maria-with-an- eye, though not black any more ... go figure.)
I notice the same kind of thing happening with European place names. For instance
Robert Browning, who was a well educated man with a good knowledge of modern languages, rhymed Calais with, of all things, 'malice'.
What happened to change it? Fashion is always the great unknown ... but perhaps mass education, cheap holidays and, previously, lots of European wars might have swung public opinion around. Also Hollywood. In the US the Spanish sound of
Maria would be natural, just as it is still natural for them to use an ee sound in
Sophia where the Brits still stick to Soph-eye-a. So if there were some Maria-with-an-ee actresses and/or characters in 1920s-30s movies, they would seem glamorous and exotic and worth copying.
If you want historical accuracy, I don't imagine anyone has ever pronounced
Miriam with an -eye-. Depends on how far back in history you want to go.