In stores, manufacturers purposefully max out brightness and contrast, among other settings, to make their TVs look artificially "better" than the competition. We know that "better" actually means "we jacked the brightness, contrast and colour settings as much as possible so you would buy our TV."
This isn't done only on the ones hooked up on the store shelves-they actually come that way out of the box so that when you set up a new TV, its set to the same blinding "torch" mode.
Unfortunately, this means your brand new TV doesn't look anywhere close to how it should, consumes upwards of 100% more electricity than it should, thus shortening its lifespan by around 50%. Not to mention that it's literally bad for your eyesight to watch TV at such settings. Various university studies suggest that the extreme brightness of the TV (or anything, actually) can, in the long-term, cause cataracts. Also the "white" on a non-calibrated TV, especially in Vivid and Standard modes, is far too blue, which inhibits the release of melatonin in your brain. That, in return, will disturb your sleep pattern. As a way to combat this, Apple actually has a "Night Shift" mode that gives its devices a warmer colour temperature, as well as "True Tone" mode to make the images as accurate as possible.
Think of it this way: when video editors, photographers, or graphic designers need to collaborate on a project, they need to make sure that their video/photo/design will look the same on each individual's display. This is done by calibrating each display to a specific standard. If you can afford the money to buy a TV, then you should also set aside the budget to have your display professionally calibrated by an ISF or THX certified technician.
A basic (two-point) calibration will cost around $250 and a full-fledged (10-point) calibration will cost around $450. Considering a properly calibrated TV will easily save you a minimum of 20% in electrical consumption and potentially double the life of your TV (not to mention your eye-sight), it's truly a must for any TV buyer, videophile or not.
Home theatre owners will note dramatic changes in picture quality following a proper, comprehensive calibration. At first, the image may seem inappropriately muted or dark. But in fact, these new levels represent the image as the filmmakers intended it for viewing in the dimly-lit environment of a movie theatre. For example, most TVs are set to around 160 foot-Lambert of brightness out of the box (or higher) where a properly calibrated display should not go beyond 35 foot-Lambert in brightness. Once viewers get used to the calibrated image, they will notice the lesser quality of an un-calibrated system.
After all, if you need a floodlight, wouldn't it be cheaper for you to just buy a floodlight?
Photo: courtesy of SpectraCal