I don't understand why people get offended when talking about pickup specs. As if anyone wants to try a hundred pickup sets and have never develop a sense of why some sound more pleasant that others to our own ears. I've learned to avoid a lot of pickups based on knowing specs I've come to not like in a pickup.
When talking about ceramic pickups, the ceramic doesn't really matter, it's the steal pole pieces that matter. 95% of this discussion is actually AlNiCo versus steel. You could slap an AlNiCo magnet on the bottom and the outcome would be the same, just with a weaker overall magnetism. It would be sort of like a P-90 in terms of materials.
Steel is much different from AlNiCo for two main reasons, its more conductive, so you get more eddy currents, which makes the resonant Q factor low, so they sound more punchy and less ice-pick, in general, the other difference is that steel has a higher relative permeability than AlNiCo, over 1000 mu rel versus about 5 mu rel, so the difference is in orders of magnitude. That causes the inductance of a pickup with steel pole pieces to be higher than AlNiCo, therefore lowering the resonant peak frequency, and that's probably the main reason people wouldn't like ceramic steel pickups, they have a low Q factor and a low resonant peak, all else being equal.
You often find the DC resistance of a ceramic steel single coil to be 6.5k to 7k, especially the Mexican made Fender pickups. A lot of wire like that will increase the inductance, but the steel increases it further, so the inductance for a Mexi single coil is often around 3.5 henries, which is high, it can make a single coil seem more like a little humbucker in terms of tone. If you slip the steel slugs out and put AlNiCo poles in the pickup, the inductance will drop to about 2.5H, which correlates with the vintage Strat sound that was made famous by people like Dire Straits, taking advantage of the pristine clean sound of low output Fender single coils.
But you can get a ceramic steel pickup that will sound closer to an AlNiCo, some Chinese cheapos come with ceramic steel pickups with a DC resistance of only around 5k, essentially they're underwound because they're cheap, but the end result is that the inductance lands closer to 2.5H like a vintage Strat pickup. Even though they sound more like a vintage Strat, they usually come in cheap, otherwise trashy guitars that cause you visualize anything other than a vintage Strat.
Even though the relative permeability of steel is five hundred to a thousand times higher than AlNiCo, the inductance is not increased by that magnitude because when looking at the overall magnetic circuit of the pickup, the majority of the path is air, and that limits the multiplier effect, but if you look at a Bill Lawrence Q filter, it has a full ceramic enclosure, and in fact the Q filter achieves about 2 henries of inductance with merely a hundred or so turns of wire, as much as a Strat pickup with about 7000 turns of wire, so when the air is replaced by high permeability material, then the multiplier effect does become very substantial.
Electrical steel has a higher permeability that AlNiCo because it has many many many more free magnetic domains than AlNiCo, but other kinds of steel used for high strength don't, electrical steel is formulated for the purpose of having a high mu rel. The fact of AlNiCo having fewer free domains is what makes it a "magnet", the polarity remains stuck in a given direction. There's a cool youtube video where a guy uses a guitar amp to hear those magnetic domains moving around in what appears to be a piece of rebar