Different companies hold different aspects of the Marvel license. DST's license allows for figures under 2.5" in height and no playsets or vehicles. Hasbro apparently can make vehicles for their lines.
and that is my issue with it...Superhero Squad came out after Minimates, and my understanding from what has been said about the license in the past is that they didnt want the vehicles for the Minimates conflicting with the vehicles from Toybiz.
Now that Toybiz isnt really an issue, another company (granted, one of, if not the largest toy company in the US) has stepped in with their own line of 2" figures and is able to do all the things that AA and now DST are not.
I just think it seems like a raw deal.