That introspective lasted until she released Beautiful Stranger and Music, the later of which was a more commercially accepted album. Note that the title track from ROL was the only song with any real traction going for it. Frozen, in spite of the huge hype it had, was a middling hit and there was the big controversy about Drowned World (only released outside the US and the video showing Madonna being chased by motorcyclist photographers ala Prince Diana right before her death, which pissed off US fans as there was a huge gap between Ray of Light and the next US single ("The Power of Goodbye"; a middling hit most famous for being licensed out to the WB for use for the promotional campaign for Felicity's debut episode, and the less said about "Nothing Really Matters".
Indeed, I'd argue that Ray of Light is an overrated album with only two decent songs: the title track (Ray of Light) and Swim, which itself is a bit maudlin track but haunting, especially given the backstory behind the day Madonna recorded the vocals (TL;DR she had just found out that Versace, who was a close friend of hers, had been murdered hours before recording the vocals for the song).
But yeah, Madonna was super serious and "mature" until Ray of Light's promotional campaign ended as she followed the album up with Beautiful Stranger and went back to doing catchy pop songs.
(Also, I'd make a case American Life MIGHT have been better received had the title track never been recorded let alone released as a single)