MB happened due to greed, jealousy, Arrogance of diff ppl which culminated in war...Dont blame Draupadi for it.
If draupadi was only arjun's wife then cheer haran would not hav happned but MB wld still occur...for some other reason.
At the end of each yuga there's major destruction which gives way to next yuga.
MB was an example for the coming yuga kalyug to show how things r going to be.
So MB to hota but draupadi wld not be an important character.just another wife.