Some OS "Open" and "Close" files automatically for the users. Are
there any problems with this approach? Give pros and cons.

I'll give you a con. Lets say my windows explorer, which is used to
move files around, decides to open my video file that i clicked on to
show me a preview of the video without me asking for it. this is
called a feature. however, because the file is now open, i am
precluded from moving the file, and since moving and otherwise
administration and organizing files is supposedly the main purpose of
the windows explorer program, it has just become amazingly useless and
frustrating.