i was watching the commentary in TTT with Peter Jackson Fran walsh and phillipa boyens and they were saying that they originally had a clip that would have been in fotr when the fellowship got to lorien and aragorn was reflecting on when him and arwen first met or their engagement or something but it never made the cut, that arwen and aragorn pic could have been from that
The Orcs were chasing them because it was in the book. 😉
And they don't have it in EE because the entire scene will be different. In the supposed scene where they are being chased, the Galadhrim (Haldir, etc.) are supposed to aid them...(that's why you can see an arrow just ahead of Aragorn in one of the shots)...but the scene that ended up in EE is just the scene where the Fellowship were first found by the Galadhrim.
Now, I think they used the current scene that we have now instead of the Lorien chase scene because it's either:
1. It's too time consuming already, or
2. We all know outside Moria that Aragorn said that the Orcs can't go under sunlight, but in those shots, it's clear that the Orcs are chasing them at daylight. It could be a mistake in consistency. But then again, they could just manipulate it through digital grading like the scenes in Edoras. I don't know.
😉