I listen mostly to jazz (predominantly small group), classical (predominantly chamber), blues, "classic" and "prog" rock, bluegrass, reggae. Larger scale jazz and classical are more a speaker thing.
I consider the strengths of the KSC75 to be inline with your observations. I would also add comfort, which is a critical issue to me. Overall I find them to have neutral presentation that is really somewhat midrange centric and that is a sonic signature I value. I've used Grado cartridges for the past 40 years so that says a lot about the sound I like.
They are not bass heavy but I find the lf presentation to be musical. I don't enjoy having my skull bashed about by point blank bass. For that type of energy I prefer the speaker/subwoofer/room interaction.
Everyone hears differently. The size/shape of your head and ears determines a lot with headphones as does your overall preferences to tonality and the volume. Some of this is also age dependent. I did very unwise things with headphones and concerts as a teenager. My psychoacoustic perception has changed over the years and I have some hf loss in my right ear.
Something else to consider is the signal. At 60 Ohm and 101 dB/mW sensitivity they are relatively easy to drive but will benefit from more amplification. In escalating level of listening satisfaction (high bit rate MP3 and FLAC from portable and computers, Vinyl and tubed CD in main):
Portable: Sansa Rhapsody E280/Rockbox r21150-09053
Office: pc AudioEngine D1
Home Office: pc via optical to Yamaha RXV995
Main: Anthem Pre2L (4x6922) class A high current
For many this driver represents an ultimate answer, for some it's a shrug and a "meh". Reality is generally somewhere in between.
I highly recommend you pick up set of the PartsExpress disposable headphones and get them off the clips. It allows for a much better positioning on the head and is a fundamental improvement. Drilling and changing pads is the next step. There is a lot of performance to wrung from these drivers. Combined with the dirt cheap price and the ease of DIY they are deserved of their cultish devotions. Or not.