I imagine, ironically much of that shot isn't CGI (remember Ady built physical model walkers for this too and the AT-ATs in this shot don't seem to move much because of the distance and we are seeing them head on).

The bits that definitely are (like the strangely galloping/hopping scout walkers) look unnervingly real.

There may be a touch of the shock of the new here as in the original footage the image is more blurred which hides a lot but makes no sense.

Why invent an optical enhancer that substantially degrades the image being enlarged?

It does look like someone has dropped HD footage into a SD sequence for a few nano-moments, I suggested having a faux autofocus which may ease the eye into the image but I think the image itself is more than fine.

However the opening shot of the walkers in the far distance, before we see through the binoculars looks too static (the walkers don't seem to be moving at all).