eh, depends. I use them quite a bit in some games. Persona and the FF, but you have to know what you are doing, and they are mostly useful on stronger basic enemies or minibosses particularly.

But yeah, pragmatically, the learning/experimentation curve for status effects is too high/annoying for most players/playing. They require a lot of experimentation and remembering weaknesses or how to stack them.

The secondary effects they have in persona is pretty cool, a lot of them up the crit rate substantially, but also they can transfer to your characters if you 'touch' them with a normal attack.