Arguably there are lots of films which could have done with being 4-5 hours long, and were compressed to match conventions and hardware limits for 'movies'.

Lots of novelizations fall into this category. Most decently dense and serious novels cannot be done justice to in 2 hours. The new TV formats have enabled substantial stories to be told well.

The Godfather parts I and II is just one story cut in half in a convenient place. Why not cut it into 4 50 minute eps and an 80 minute finale? (Edit: this substantially underestimates the running time of the first two Godfather movies!)

People are going to pause your thing to go to the toilet anyway. You might as well indicate to them when's a good time to do so.

Obviously there are also quite a few movies where 90 minutes is plenty. Both formats seem needed.