Same here, I think they didn't show that trailer here in Germany...or at least I didn't see it.
Even in the US, video game trailers (at least, circa 1995) were regulated to the realm of trade shows and industry (re: gamer) publications, with the occasional video game store outfitted with a TV monitor (ah, Babbages...) that showed such video. This is a far cry from the present, with GameTrailers.com and GameStop with it's own in-store TV network.
There were, of course, video game commercials, but according to the CIC the WC4 commercial only played on SciFi Channel (which was still in it's infacy) a handful of times.
That being said, trailers are made by the distributor/publisher, and I'd think that those making the trailers only had a handful of completed footage and a rough outline of the plot, with no necessary prior knowlege of WC lore. "A man deranged by war" has a much better hook than Tolwyn's actual motivations, but I do wish they were a bit more creative/abstract, instead of ruining the final act's surprise for us!