I wouldn't say overhyped. The Strait of Cozumel was Jacques Cousteau's favorite spot, after all. Some people just don't like guided dives, and I can respect that. But it's Mexican law: all dives are guided dives. Also, the drift makes for a relaxing and easy way to spot wildlife.
I have been to the island eleven times over the past 25 years, and have booked a (12th) trip for January 3-10 of 2024. Definitely it has changed, but it is not as overdeveloped as the mainland across the straits. The first time I visited Playa del Carmen, I drove from Boston and I parked my little five-speed ghetto Toyota Tercel on a small plaza that had a church, a school, an alcalde, and a park, and walked three blocks to the ferry for Cozumel. I left my car there for four days and no one touched it. Today that spot doesn't exist. There's the huge Playacar resort and too much coastal erosion on that side. But across the straits, San Miguel remains peaceful. Not the small fishing village it was in the 80s, but sustainable.
The big game-changer was Hurricane Wilma in 2006, which fractured the Felipe Xicotencatl and left sand all over the reefs. It is still recovering, but on my last trip, in 2022, the small scenes were excellent. Beautiful banded shrimp, big crabs, lobster, squid, and, at night, octopus. The big scenes are excellent as well. I have spotted a number of reef sharks, hammerhead, and barracuda. It remains the only place where I have ever seen a pod of seven dolphins approach me underwater. Best dive ever.
Also, the lionfish, an invasive species, are finally disappearing. When I first started to dive there, they were ubiquitous. The government has been encouraging divers to eat them and publishes several decent recipes. (It's the only fish you are allowed to take in the marine park, if memory serves.) Over the years I have found that we have to dive deeper and deeper to encounter them. My most recent very deep dive was 105 m (344 feet) just off the Playa San Juan on the north of the island, which you normally wouldn't visit unless you booked a technical dive. (Deep Exposure is my recommendation for deep/tech dives in Cozumel.) And even at that depth they were rare, although we managed to spear enough of them for a nice cookout at la casa del dueño.
I'm with Jacques Cousteau when it comes to Cozumel: a paradise not to be missed.