There are probably other materials that would also work, though... I'd expect any material used for toilet seat lids (plastic, or coated wood composite) satisfies similar constraints.
Incidentally, ceramic can become razor-sharp when broken, so the article's suggestion of making lids easier to break carries its own set of risks.
I don't think there's really anything wrong with plastic toilet seats, but they feel less good, I think, than the heavier, more solid toilet seats.
The worst, in my mind, are the foam/shag carpet covers. those just seem wrong and gross - I mean I imagine my reaction is completely irrational, but I remember once I moved into a very cheap aparment; the toilet seat was sealed plastic covering foam in a way that the toilet seat was actually cushioned. something about it really squicked me out; the first night I went to the hardware store and bought a regular solid toilet seat and installed it.
Personally, I like keeping a heavy seat and just installing a dampener hinge, though I suppose that wouldn't help if you drop it during installation.