It's a compromise.
1) For cinema a wider viewing angle is desirable to improve immersion, and the content is generally at higher resolution (they've been running 2K and 4K for years), so a bigger screen doesn't have the disadvantages that it can for TV viewing (the main disadvantage there being that heavily compressed SD content looks progressively worse as the screen size increases).
2) Cinemas tend to be shoebox shaped (ie longer than wide), so they need to make sure that people at the back can see clearly - which means a big screen.
3) They want to get as many people in as possible though, so the front rows are too close, ergonomically speaking.
Basically there's a group of seats on the centreline from about 1/3rd of the way back to about 2/3rds of the way back that get a decent image and also get something of a surround sound effect. The other seats are compromised. I spent a good few weeks in a previous job working out optimal seating positions and screen sizes for various different room configurations and uses, and the conclusion is that pretty much every space has to be compromised, either spoiling the image to meet the space owners' objectives, or not fully meeting the objectives to ensure that people see a good image.
I gave up on going to the cinema years ago when I realised that I was much happier watching films at home.
