I agree with some of the points you are making. You need to wait for people to be starved of football before you start another league. You also want to have the season end about a month before training camp ends.
Also, the gimmick thingy cost them, IMO (which you mentioned). They tried to add too much crap to the game in order to make it different. All they needed to do was tweek things a little. Different camera angles were nice but the rule changes were too much. I understand the rationale behind it in trying to appeal to the WWE crowd, but they alienated the hardcore football people in the process.
I still do not think another league will work, but at least they could have had a better chance.