Well, by the same token, you could say: 'I've never understood the desire for higher fidelity audio systems. I listen using a standard-fidelity system, and that is enough to hear bass, midrange and treble, etc, and follow the tune...'
So why bother with higher fidelity audio systems?
I'm being somewhat flippant of course, but I trust you can see my point...
Increasing the resolution of your TV, in order to see/enjoy a 4K UHD film in all its glory (thus reproducing the source format as faithfully as possible), is as rewarding, if you're into that, as increasing the fidelity of your audio system, in order to hear a high-fidelity music recording in all it's glory (thus reproducing the source format as faithfully as possible), if you're into that.
Therefore, owning a higher resolution TV, is about
seeing as MUCH of what's there (detail visually present on the screen), as clearly and realistically as possible, just the same as a higher fidelity audio system is about
hearing as MUCH of what's there (musical information on the recording), as clearly and realistically as possible.
So why would you settle for SEEING less than is possible, with your choice of TV, or HEARING less than is possible, with your choice of audio system...?
For enthusiasts of either of the above, the exercise is about experiencing both SOUND and VISION in the most REALISTIC and LIFELIKE way possible, and therefore to the highest standard/resolution that the audio or visual format played is capable of delivering. That is why we own high-fidelity audio systems and high-resolution TVs, in order to enjoy both our favourite music or films to the highest sonic or visual standard - it's as simple as that.
That's fundamentally not what it's about. As I've said, the goal is simply to both SEE and HEAR as much of what's there as possible, and not settling for anything less! Certainly speaking for myself, that's where the pleasure is derived from, and why the required effort and expense to achieve it is worth it
Marco.