Not strictly true, as LA has horizontal seats in a 6-across configuration on their 763s (see here), and IIRC the current Recaro seats AA has can be reprogrammed to go full horizontal (with additional pitch, of course).

I haven't done/seen the math, but I strongly believe that the new seats AA is installing (the Vantage II) have a higher density, which justify their purchase vs. spacing out the current Recaros to make them go horizontal. I am 100% sure that 100% aisle access is not driving the purchase, but it's a nice byproduct of the seat.

I won't comment on AA's choice of colors (as all marketing pictures are "optimized"/retouched and make anything look good) or materials (which you can't touch on pictures) until I actually see it.