You are right in everything you say but everyone is also entitled to an opinion. As long as it isn't personal and vindictive then I see nothing wrong in giving those opinions. And after all this is a forum, debate, argue and pass comment is what happens on them.
People who have invested time money and effort into the scene are entitled to an opinion. Just because you or others don't agree with it doesn't make that opinion wrong, doesn't make it right either for that matter, there is no right or wrong. I said earlier people can dress how they like, it doesn't bother me each to their own, some of the clothing in the ad looks smart.
But people must be pretty naivé to think an advert can be made and no comment will be passed. Those who made the advert are probably pretty happy with all the talk, both good and bad, shredded wheat has had tons of free publicity.