The game is barely active as it is and it's not getting anymore popular.
Currently this game has 3 active runners, 1 being myself. The need for all 3 of the games difficulties just isn't there. And tbh it never was there to begin with.
New game Normal is slower than casual for 1 minor reason and thats the placement of the rifle. Obtaining the rifle doesn't require anymore skill it's just simply in a spot that takes an extra 2minutes to get. The route, enemy placements, and almost all items/parts are in the same places as Casual.
NG+ Normal is even more pointless because its basically no different to Casual.
Makes much more sense to have easiest/hardest rather than all 3 considering Normal is practically the same as Casual
to be honest i agree with stevenmayte when i checked the normal board it was barely ran i think the last run was around a year ago and due to placement on enemys the rifle and what not its pointless since casual is the fastest to run on both new game and new game+ and infernal offers a slight challenge also it was not on the main screen it was actually in a filter so it was not going to get too much attention unless someone really wanted to look for it