I think there are a few reasons why WWI is not as widely portrayed as WWII.
One reason is that the war was very stagnant throughout most of the duration. Other than a few dramatic offensives toward the begining and the end, not much happened that inspired interest. Most battles were very similar in nature... heavy artillery, poison gas and a charge over the top. The few battles that were different, were usually such horrible things that most people didn't want to remember them (Verdun, Gallipoli....)
Photography was much more difficult in WWI, which means there is less source material to go from. In WWII almost any soldier in Germany, England or the US had the ability to bring a camera into battle. There were dedicated personnel to document battles, and cameras were a common occurance...even in color! Propoganda and news films were everywhere, which gave the home front some sense of what was going on. The people were kept updated constantly, and even civilians were able to see images of tanks, planes and ships.
WWII also duplicated much of WWI's events on a larger and more dramatic scale. WWI had some tanks inching along and looking angry, WWII had true war machines charging across the desert at amazing speeds. WWI had the flying circus of biplanes, WWII had 1,000 bomber raids against Germany with rocket and jet fighters screaming up to meet them. WWI had submarines, WWII had more and bigger submarines as both enemy and ally. WWI had Jutland and a couple smaller battles while WWII had the hunts for the Bismark and Graf Spee, the Channel Dash, Leyte Gulf, Midway, Coral Sea, Savo Island, Taranto Harbour and so many others.
WWI erupted almost instantly, WWII had decades of tension and conflict leading up to it. But the biggest is that WWI brought everybody misery and suffering for years, there was no real meaning to victory in most battles. It was a hopeless war that everybody just wanted to end. WWII had battles with defined winners, and clear results when battles were won. This gave people hope and gave the occasional positive light to the war.