Yes but that flash art style comes mostly from american superheroes comic books, specifically Marvel and DC, with those high color contrast, black shading, mrked black ink and plain colors.
It is pretty unrelated with woodcuts or ancient illustrations, to which TW1 posters are inspired (like Dona said, I agree). I posted the pics becoz I have the sense that many people does not actually know what is the real latest medieval and renaissance art style (supposingly that TW is settled in the 15th cen, more or less). Also, there is is late trend of webcomics, to which W2 flashback movies are inspired as well.
De gustibus, of course. I won't argue about personal taste here (altho I will defend with blood and flesh those flashbacks until death LOL). Just saying that W1 flashback style is certainly not closer to medieval\renaissance art at all, they're mostly photoshop quickpaint concept arts. DeviantArt is full with those paintings more than with W2 webcomic style flashbacks.
I think they've chosen to follow the trend (DA2 also has a similar art style in cutscenes). Webcomics and comics on ebook\ipad etc are the future. Well actually they're already here now...