There is nothing stopping you swapping out the motor pins to swap X and Y axis around so that the X is the longest but it may get confusing due to the position you stand at, so might be best just to leave it that way.
Also remember I am talking about Machine Coordinates, you can and will use work offsets, the normal one is G54 and which is normally what you are seeing in the DROs so you could set the work offset to be zero in the centre of your table and have both positive and negative coordinates for X and Y.
Hope I am not confusing the matter LOL, it sometimes takes a while to get your head around these things, especially if you are fairly new to CNC.
Hood