Why are you assuming the only end goal is a screen in your house? There's also theaters, blu-ray releases, etc. The picture needs to look go when it's measured in feet, not just inches.
Also, "everyone" does NOT have their display calibrated differently. Many people who are into home theater equipment has their displays professionally calibrated. Stop assuming the rest of the world is fine with your low standards. Also, there is no "calibrated differently". Things are calibrated to a standard, not to what the technician thinks looks best. It's done right or it's not really calibrated. Think eyeglasses. There's the correct prescription, then all the other prescriptions. These isn't a range where you're good or close enough. It's correct or it's not correct.
Finally it's done because it's the right thing to do. You don't half-ass things because some people don't care. This is a forum about Apple and their products. Take this attitude to a dedicated home theater forum and you'll soon learn that there are people out there who care a lot more about having things "correct" than the average consumer.
I don't understand this attitude that Hollywood should only be putting in enough effort to please the lowest common denominator.