Madonna's biggest problem with her age is that she's a one-trick pony. She's not a versatile actress or singer, and her career was built on making sexy youthful pop songs. Her image never matured, and neither did her age.
Showbusiness forces images on people all of the time. Her first album released, and it was a smash-hit, she was some sexy young thing making provocative pop songs. I don't know if it was an image she voluntarily wanted to continue putting out, but managers and contracts and companies will most often stonewall you into whatever sells. Sinead O'Connor, by comparison, was one of the women that was going to be forced into the "conventionally attractive young woman" archetype for her first record and that's why she's kept her head shaved for the past thirty years.
I'm sure there came a point in Madge's life where her only options were quit entirely or continue making whatever the labels wanted her to shit out, but that was years ago.