Not only do people perceive colors differently, and have their own
differing opinions on aesthetics, the ambient light in a home theater
can cause the viewer's eyes to "white balance" in such a way that even
if the display is calibrated perfectly, it will appear tinted one way
or another.

I think that outside of this group's demographic, most people simply
don't understand the controls, but I know that many who do not have no
problem with adjusting them based on the "more is better" philosophy. I
remember some superbowl games at friends' houses that nearly gave me
flashbacks. Most people who do fiddle with the controls tend to make
everything too bright, in my experience. They never seem to notice that
anything white starts to bleed out and cover half the screen.

If you're producing material, though, the controls are needed and
applied differently. If you're doing video or graphics work, it's
important for your display to be as neutral as possible. At the
extreme, even the room lighting and decor need to be chromatically
neutral so that the production process does not skew the original
image. Likewise, recording studio loudspeakers are designed to be
completely flat in their frequency response. It might not sound very
good, but it ensures that what the producer is hearing is what's
actually being recorded. If the consumer wants to turn every eq knob
all the way up, that's his option.

When I set a system up, I check to make sure it's displaying a full
range of grays and that the tint looks right. Using a calibration disc
usually just ends up reminding me that I can't afford a $5000
television set.