Let’s talk about this in the context of film photography.
50mm prime lens
I have always ranted about how my 50mm lens is being too up tight and making my photos to look very ‘squeezy’. It’s a good lens if I want to stand far for street photography. 50mm lens is also good for up close portrait because the bokeh effect is smoothly creamy.
But sometimes it is just frustrating to have to move back to get a larger picture. And sometimes your limited space doesn’t allow you to step back. So, I thought a 28mm lens will solve my problem. To me, I like to travel. So I guess a 35mm might still be tight for travel shots (scenery, monuments, architecture).
Shooting experience with 28mm

Fuji Pro 400H, Singapore (2017)
Liberating
Most of my cameras have only focal length of 40mm to 50mm. Hence, when I use a 28mm lens, it felt like an instant liberation. I can stand at the distance that is usually ‘just nice’ for a 50mm but now having the foreground or background included. This wide angle lens is definitely more versatile. It can be used for travel, street and many more.
28mm on Leica M6
If you haven’t already know, rangefinder camera such as Leica, the image you see through viewfinder is not the same as what the lens sees. Hence, to assist users to place subjects within the frame, the viewfinder of rangefinder has included ‘frame line’ in accordance to the focal length the users use.
The maximum frame line for Leica M6 (or almost all film Leica) is 28mm. Beyond that, you need to get an external viewfinder.
For a short-sighted person like me, when I look through the viewfinder with my glasses on, I cannot see the complete 28mm frame line. Meaning when I frame my image, what I see is probably about 35mm. But my lens captures more areas in reality. Let’s see the example from below:

Fuji Pro400H, Singapore (2017)
You won’t have this issue if you don’t wear glasses. But I refuse to wear contact lenses.
The need to get near

Fujicolor Japan 400, Singapore (2017)
Zone focusing

Fuji Pro 400H, Singapore (2017)
For film photography, it is sometimes the pain in the ass to try to manual focus. Especially when we do street photography. Hence, zone focusing is super handy if we want to be super quick in action.
Conclusion
Overall, 28mm lens is a good investment and the best wide angle lens to go for. It can be used for travel, group photos, street, architecture, etc. However, the digital trend now is to use ultra wide angle for architecture photography. The problem with ultra wide angle is the distortion: the fish eye effect.
Furthermore, ‘less is more’, so if you don’t know how to utilise wide angle properly, your photos will have a lot of junk around your subject.
As for film, I haven’t seen anyone using ultra wide lens yet. Most of us stick to the common 28, 35 and 50mm.
In conclusion, I don’t enjoy shooting with 28mm. One day, I might get a non-Leica 35mm lens for Leica M6.
Again, in photography, it’s endless of hunting for gear after gear, if we are not satisfied.
Are you not aware of the .58 alternative viewfinders available on M6’s where you can see the 28mm lines with glasses on?