The reason we have so many different aspect ratios in movies dates back to the time of analog mechanical projectors. In those projectors, there was an actual film sliding along between the lamp and the lens from the top to the bottom. In front of that film there is shutter, that opens when a picture was entirely in the frame, and then closes again before it moves out. Those projectors where were only capable of producing a movie at exactly 24 frames per second (fps). Any slower and you would be annoyed by the gaps in between the frames. Any faster and the shutters wouldn't be able to keep up with the frame-rate and you would see the picture sliding in.
Filmmakers always wanted to go bigger, because it meant they could reach a larger audience, and a bigger image also just leaves a bigger impression. But there was a limit on how far you could stretch the image from the original film size to the projected image on the screen without loosing a lot of quality and sharpness. After all, a film itself always contains a bit of grain and any lens suffers from impurities in the material as wel physical properties such as chromatic aberration and refractive index. Now, you could start with a bigger film, but you could not make the frame itself any higher because that would require the entire film to run faster. So the only way to produce a bigger picture whilst still maintain a high quality and sharp picture was to go wider.
So wider they went. They went from the original 35mm film to 65mm, and all the way up to 70mm. And with that, starting off from the original 1.33:1 a lot of aspect ratios were introduced, with 2.36:1 being the most widely adopted. The widest commercially used aspect ratio was Ultra Panavision 70's 2.76:1! Famous movies that came out in this format are Ben Hur and The Hateful Eight. There are not a lot of projectors left in the world that are able to display these movies in their full aspect ratios, so most commercially available copies are cropped.
Then, in 1970 IMAX introduced their 70mm projector with a special vertically closing shutter system that was able to open and close much faster and stay open for a longer period. The system had an aspect ratio of 1.46:1 and was capable of producing a 586x magnification from the original film. This had a lot of impact. Finally they were able to fill an entire cinema wall from top to bottom.
The introduction of digital projectors again changed everything. These projectors are not limited by factors that a mechanical system would introduce. They are capable of producing much higher frame rates. They are also capable of producing any aspect ratio without having to switch projectors or lenses. This allows people to enjoy any movie without cropping or loss of quality in a any theater. Even though there are no technical limitations anymore, directors would still chose specific aspect ratios or camera systems to create an intended cinematic effect. This is why 2.36:1 still is the most popular aspect ratio for movies.
Now it goes without explaining that TV's were always capable of reproducing all aspect ratios, because they are also not limited by mechanical factors. The only implication it has is that you will see black bars on either the top and bottom, or the left and right hand side of the picture. In order to keep the black bars on the left and right when you're watching a tv show with a 4:3 ratio about the same size as the bars on the top and the bottom when you are watching a 2.35:1 movie, the tv industry settled on a 16:9 standard ratio for tv's.
Do i mind these black bars? Absolutely not, because it allows me to enjoy the movie to the exact artist intent. Also it acts as a reminder of the technical possibilities of the time that the movie was created.
I hope that, now that you know a little bit more about the history of aspect ratios and projectors, you too will be able to enjoy watching them on your television the way they are meant to be seen. Even when it means you'll have to look at some black bars every now and then.