not to weigh in on what a program should and should not do, but i would love to be able to open abc files with out having to export to midi first. i would love to be able to open the music xml files that come from some of the people i play with.
I am a big fan of http://www.thesession.org which posts music in abc format. i would love to copy and paste the text from the browser window straight into an abc window in notation. one less step one less file to clean up ....one less thing .