John Harmon likes that meta-awareness stuff. Remember the intro to season 3. The whole 'We're gonna finally be fine' thing? He's very well aware the way fans reacted to season 4.
Harmon didn't make the trailer though, this is an official trailer released by NBC and Sony, and studios tend to be very diplomatic about this sort of stuff. It's odd because 1) they're effectively insulting the work of a bunch of their former employees, and 2) they're admitting that season 4 was crap while simultaneously trying to sell season 4 DVDs.