Heh, it's not really an addition, although the ability to enable it on first boot is. It's really just the "beat the game flag" that the game already sets on beating 8-4 anyway =P
Did the original game have a level select? outside of the warp pipes that is. I love the game but damn if I ever played every stage in the game, warps and vines are my only methods of beating it lol.
I regularly play through warpless runs. Have got over a million points too, not every time but I usually at least come close.