Back in the early seventies, so many of us played Strats, largely influenced by one J Hendrix. Amps had no master volume controls. As the music of the day began to become heavier and more muscular, we needed to get more grunt from the strat, especially the bridge pickup. Companies like Mighty Mite and DiMarzio appeared and brought us hot replacement pickups. This allowed us to ram bigger signals into the front of our amps and get more....RAWK!!!! Many of these hot pickups were no doubt ceramic magnet jobbies.
However, some of us, myself included, noticed that this detracted from the original subtleties of our guitar's tone. As the years have gone by, amps have become more high gain and pickups have developed outward in more than one direction....those for high output and those seeking to capture elusive vintage tones. With the higher gain amps, it is now possible to use a small signal from the guitar, with plenty of the wood's subtle nuances, but still dial in a great big rock sound.
Now I can only generalise here as there are exceptions, but I would venture to say that largely, if someone is looking to set up a Tele or Strat or similar for the classic old sounds, they are quite likely to find themselves using Alnico magnet p/ups, whether they realise it or not. Conversely, if someone is building the metal sound of doom into an instrument, it is likely they could be using ceramic magnets. As I say, this is a generalisation, and other things come into play, like the coil windings of course.
I think that the state of play today is very good, that we often appreciate the acoustic qualities of our chosen plank of wood, and we are able to use lower output pickups to get that into our amps, and let the amps take more of the workload for getting the drive we want. That way we can have huge rock tones but still have the articulation and subtleties within that wall of rauch. It seems to me there has been a great resurgence of interest in Alnico in the last decade or so, in speakers as well as in pickups. We are all becoming much more knowledgeable (which is great but I wonder if sometimes it makes our lives harder! Ignorance WAS bliss!!...and cheaper....)
At the end of the day, it is the ear that counts....if our ear is pleased, we are happy, but it's nice to have places like this to read and learn and discuss, as the pickup trial/trail can become expensive....