Using CTRL - (minus) once or twice will zoom out enough making the visible area bigger while leaving the minimap big enough to navigate by. CTRL + will do the opposite, however a word of warning, if you have a slower computer, it'll have to work harder to draw the extra if you zoom out and performance may well suffer as a result. Note to anyone using IE: it'll let you zoom out to 10% and my machine can't cope at that point and effectively crashes, chrome and firefox limit you to a min of 25%

It would make it easier for playing on a smaller screen. Perhaps making the map semi transparent when navigating as well.

Some times the mini map gets in the way when going in a northerly direction, but you need it open to navigate. It would be more convenient if you could open/close from the keyboard so you can keep moving on the mouse. Alternatively allowing keyboard movement would also work for me.

This would be easy enough to add, I'm just curious about the reason behind it.