Cassette tape

"Is there any usefulness?"

That's an odd question.

What's "useful" about a cassette?  Other than novelty to possibly relive your youth, more clutter the wife will complain about.

What do plan on doing with a cassette? Transfer a record, then play in your car? I wasn't aware one can still get a TDK or Maxell at the drug store.

Does anyone have a functioning cassette deck in their car?

Go with the table, and R2R if you feel so indulgent. R2R is very cool, but are you willing to shell out the dough for albums? Also, the inevitable repair bill? 

A table based system is already a ridiculous method to listen to music in this day and age,  even though I haven't stopped since the 70's.

Cassette at this point seems like pure nostalgia, and nothing else.
Perhaps it's the tape hiss between cuts? Oh, forgot...Dolby feature eliminates that(snicker)

Cassettes are great. They should bring them back. Low noise, high dynamic range, musical and full range. What other medium can you say that about? Tape is a natural medium. It breathes.

Does anyone have a functioning cassette deck in their car?

I do in my 03 Lexus. And I use it regularly as I do my Dragon and my R2R at home. Loads of fun and pleasure.
I say go for it and enjoy.

I use Nakamichi 682ZX on a regular basis.Great for high quality background music. I use nothing but Maxell Vertex tape - the best there is - and no dolby. Second best is TDK MA-XG. With my deck the difference is very significant. Both are very expensive, Vertex is over $100 each.