I can only guess that it might be for 2 reasons.
1. Anarchy was the first Vogon server, if I recall correctly.
2. I am assuming players feel more comfortable w/the full spectrum of weapons available.
IK gives a player one weapon w/2 diff. modes. Pass through & non pass through. IMO for most new players that's just not enough. New players get frustrated of being tied down to one weapon and either leave or stay to learn. On top of that the rail is an accuracy weapon, you get a shot w/a brief recharge time.
I remember going against AbsoluteGojira. I use to get disgusted w/his one shot one kills. I still do at times, but it gives me a goal to attain to. For most players i am sure it can be maddening to get railed over and over and over and over again >] You only get better w/practice.
In the end, it's probably fustratation.
ps login so we don't have to keep approving your posts! LOL