I used to buy cassettes because they were cheaper back in the day than CDs. I would buy a cassette of albums I was unsure about then I would upgrade to CD if I really liked the album/band. I do still have a kind of liking for cassettes. I liked dubbing recordings on them back in the day and they were kind of conveient for the car too. At least it was easier to store cassettes than a bunch of CDs in your car. I'd still rather hear a CD or cassette in the car rather than fumbling with my phone for music even to this day though (my cars CD player is busted though, and no cassette deck.. its a newer car).
If I find newer issues that they have for sale for collectors or nostalgia or whatever, I may consider picking a few up. I bet they're like the LPs where they're crazy expensive though.