I listen a lot to my one hundred or so cassette tapes of the NPR 'Oasis' and 'Hearts of Space' music programs. I recorded these back in the early to late 1990s. They were mainly recorded on a nice Sony mid 1980s K-555ES-II 3 head dual capstan deck (still have it, belts never replaced). Some tapes were recorded on a somewhat lesser Aiwa 2 head auto reverse ADR-707 (1990-93) deck but they sound fine too. These CR2 (Type II) mostly 90 minute tapes still sound great to my ears (assorted brands; TDK, Fuji, Sony, Maxell, etc.). Maybe the highest frequencies don't extend to the typical CD level but the lows, mids and highs sound exceptionally good. I probably can't hear above 15,000 Hz in any case. Lately I have been listening with various decks to include a nice Denon 3 head dual capstan DR-M30HX deck (1986-88) and what I hear is likely as good as it was when it was recorded. Also have an Aiwa AD-F800 3 head dual capstan, Sony TA-K555 3 head dual capstan....and finally, Nakamichi BX-100 and Luxman K-111 & K210 two head single capstans. All competent nice sounding decks.
I also listen a lot to CDs using good equipment (Cambridge Azur 640C, etc.), 2 & 3 way vintage speaker systems (JBL, Electro-Voice, Altec, etc.) so it's easy for me to compare tape (and vinyl too) sound qualities with CD.
Bottom Line: Nothing wrong at all with high quality cassettes when they have been well recorded, cared for, and played back properly on high quality well maintained equipment. I've been into this hobby for over 40 years and I know from experience what sounds good to my ears. That said, I'm not going to run out and look for a brand new deck - those days are long gone. Many good older used decks are out there real cheap. That technology more or less peaked in the late 1980s or early 1990s and the newer decks are likely not built as well. My 2 cents worth.