As author of a program which can import MIDI, I must agree that this is not really practicable unless the MIDI was created by hand in a sequencer, not played on an instrument. The lengths and timing of notes can be much too variable. A "real" note has in mots cases an active sounding time and a silent gap, but a program will interpret this as a shorter note followed by a rest. Quantisation can help, but is only a partial answer.