There’ll always be differences in communicationstyle and some of those will because of cultural diversity. To appreciate that all you have to do is join a foreign bulletin board and see how folks interpret and understand what you’re saying 
Joking aside, if you’re a riding instructor then it is important to give criticism that is detailed, instructional, helpful and motivational no matter where in the world you’re from.
I’d say though that that’s not the case when it comes to commentating on a performance or judging even if it come to that. I’d also say that the reason why some folks make superficial comments then is more likely to be that they don’t know any better, don’t want to hurt feelings or are like I said in my first posting here. In that context when folks make subjective nasty comments I’d also say that it’s because they don’t know any different and want to hurt feelings or are maybe just jealous and/or frivolous and vexatious.
When it comes to commenting on dressage which is based on opinion and so arguably a “subjective beauty competition” then I’m thinking that you’ll get those that comment superficially because they actually genuinely don’t know what they’re supposed to be looking at and judging.
The best example I have this is from my wife’s dog showing world. We owned a fantastic golden retriever who ended his days as a Champion and with 26 challenge certificates. He was a line bred Royal puppy and came from a record holding litter which ended up with 7 champions. He was purpose bred and always destined to be good and great and he was. He was genuinely the most symmetrical, powerful and balanced dog I’ve ever seen. (but then what would I know, I’m in to horses ) When he was a pup though, he did however have a few black hairs on his nose!? On one of his early outings he went to a show under a judge that Sue and her sister said they wouldn’t normally go to but we had some bitches being shown too so they took him for the ride and the outing and experience. As it happened he came 4th but we know that was because the judge knew the handler always had good dogs. The judge also said “he’s got some black hairs on his nose” . The handler said “You don’t say. But what do you think of his conformation and stifles?” Truth be told we know this particular judge wouldn’t have known what to think about anything more complicated than the obvious to the blind.
One of the things I’ve always thought competitive dressage (and horse showing) could do better is engage the audience and the competitor come to that.
Folks win and lose and most often no-one knows why.
Critical detailed comment highlighting good and bad points is genuinely helpful and informative and when scoring is based on points deducted for not being “perfect” or “true to standard” then it makes sense to me to say what is wrong and away from that standard and not what is right.
