Like we said, it is also advised to use a downloader to help when you have spotty internet.Internet access in America sucks even in big cities when you compare to Europe and some Asian countries like South Korea and Japan. In fact ironically rural Europe tend to have better internet access than cities because digging is so much cheaper when you don't have to care about sidewalks or anything else like that, which needs to be restored. This means it might be easier to get fiber in a house in the middle of a field than it is inside a big city. The percentage of houses on fiber also tend to go up if the 4G/5G coverage sucks.
Having said that, I would be very much against lowering the quality for the sake of download size. If we are ever to be serious about that, a better solution would be to have the ability to upgrade. Imagine having one file for each release, so to get a new version you can download a addon file you add to your existing game, which adds the new graphics. The script file will then have to be overwritten each time, but being pure text that's a few MB. Using this approach you don't have to download unchanged graphics each time.
The problem with this approach is that it makes development more complex and will probably slow it down. Commercially this approach is usually used with finished visual novels where the addon file is bugfixes rather than added content. As such it's much less of an issue that it makes script writing and hence development more complex because it's way more complex to figure out where each image file is located.
As for the update version, Runey does that so I know it's possible with Ren'Py. Though with how well people read, that can still cause a lot of issues as well. You put each update in its own set of .rpa files. But as I was saying, it causes issues if you don't get all of them, or install things correctly. It's generally safer to get the whole update.
True, though I have also seen some of those that change more than the quality, so use at your own risk.And, alternatively, a lot of games uploaded to this site get unofficial compressed versions made by third parties that people can use if they want a smaller download.