They are digging into the benchwarmers and minor leagues for characters aren't they?
These are minor characters in the grand scheme of things. However, they have one thing in common. The writers can do lots of things with them and Fanboys will not cry and scream "Foul" and "Not in Continuity" and "How could you do this to my favorite character?:!?!?"
These are characters that people will for the most part go into without knowing anything about them. People will be going to see a cool movie, rather than Marvel Comic Movie. (Or television show/cartoon ... it all extends). (Or in the Super Six's case, they will be going to see an Anime...)
Think about the problems Marvel has had with most of its mainline comic movies (Daredevil, Electra, Ghost Rider, Fantastic Four, and most of the Spider Series). They all didn't quite fit the comic character style and storyline. The fans cried, yelled, and screamed. (we are filtering out the acting issues.) Normal people didn't go see them because these were Comic Movies, obviously for comic fans. The Avengers sequence were all continuity reboots (and listed as reboots) and they were not all received warmly by the fans. Avengers 1 was the first one that didn't take any flack from anyone and did really well. (Arguments can be made for Cap 1 and Iron 1)
And the cartoons have all been hit or miss, though Ultimate Spiderman seems to be doing well.. mostly because it is tossing most of Marvel Continuity out the window... yet still using all those cameos to their advantage.
So yah. Smart Move. Use some properties that the fanboys might like and will make a good normal movie/ television show/ cartoon.
It is a smart move to create