The Uruk-hai Culture was one of three reworked cultures following the release of Shadows. Decipher's goals in redrawing Shadow cultural lines by Race rather than by nation are unknown, but it had the result of causing a schism between the Movie block era and the post-Shadows era, since the new and old cultures do not play well together. This had the effect of alienating the playerbase, who viewed the move as a marketing ploy to force players to purchase new cards (since the old ones were now incompatible).
The Uruk-hai culture replaced the previous Isengard culture. It was the least justifiable of the reworked cultures, as it was essentially just a rebranding of Isengard without any real changes to content or what it represented. Indeed, since it lost Warg-riders to the Orc culture, it actually lost some of its defining characteristics.