The reason you do it is because you know those trades will reach Barnes & Nobles and used book stores faster than most DC/Marvel books. Like I can go to any used book store in my city and I will see every single IDW trade for Dr. Who, My Little Pony, GI Joe, Cartoon Network and others.
What you are really doing is getting more attention for your show as most don't watch BBC but if they get the trade or rad it-they might become OB fans.