If anyone has any system set up to read a piece of published sheet music and then produce a MIDI file from it, they'll soon discover how horrible and unmusical these files are - unless you spend a long time editing it.
Many moons ago I was heavily involved with a UK exam system where one of the tasks was to convert a piece of pop music and a piece of classical music into a computer project - Early versions of cubase mainly (Cubasis, or Cubase Lite) where they did have scoring editors. The candidates got marks for making it musical, and those that tried to use Sibelius did really badly. Competent musicians many of them, but the scores looked wonderful and sounded simply terrible. Nothing really has changed. A crochet (¼ note) has a fixed velocity and a fixed length - so string four of them in a bar and you have something impossible to achieve by a real musician, where every one is slightly different in length, volume and starting point. In the exam, the musicality was what got marks, and clearly many spent their time getting notes in to look like the score, and no time at all making it sound human. Examiners would click on a list edit page and see hundreds of identical notes, and be unable to award any of the musical or stylistic marks.
In my brief experiments with current scan to MIDI software, the accuracy of identifying the notes in a heavily clustered stave have vastly improved, but timing and note lengths are fixed, and that has to be done manually. We used to tell people that Cubase was pretty rough at producing scores from played in music, and Sibelius was the same at producing musical sounding music from dots on a page. They've both got better, but still they are for different purposes.