Because obviously you are there for the "story"..........right?.......right?...........RIG HT?!?!?!?!?!?!
We all know if gear was removed from raids, no one would do the raid at all unless it was completely faceroll.
If you must have a raid all decked out in Rakata before attempting EC storymode, then you have effectively removed the gear carrot from the raid. While some raiders will spend some time in there to see the sights and experience the wonders, that quickly wears off when silly mechanics operate in strange ways - like having 3 lightning spires spawn inside
the bombardment shields on the tank bosses.