I think it is pretty damn harsh, considering these cars passed the initial scrutineering checks, had the teams known that the wings were wide on the first day of competition, they would have had a chance to rectify the problem, it wasn't like they were taking the piss and trying to cheat the competition. Rules are rules, yes that is true but don't go telling people "yes your car is fine" then come around and change your mind.
Not only that, as an arbitrary % of performance, the wider wings what, would be good for 1-2% if they were lucky. A single cone strike could blow the wider wing benefits away. Would it not have been fairer to dock a number of points from the dynamic events rather than all out DQ? What harsher penalty do you now have for a team deliberately breaking the rules?
The team/s that were DQ'd deserve an apology from the event organisers, to be told your car passes, then, someone measured differently, and told them no it doesn't is absolute crap. I understand the people are volunteers but if that wing measurement is so important (as was apparent by the punishment) why the hell was it not checked and triple checked initially, saving this entire situation from happening?