Every year at my college, we had an event with workshops on various topics, including issues that affected students on campus. When the club organizing this event asked for topic suggestions, I suggested a discussion on personality differences and the pressure to be a certain kind of person. I mentioned that in my four years at college, there had never been a formal discussion about this topic (not just at this event, but in general). I knew my idea may not be chosen since a lot of students submitted ideas, but I hoped it would at least have priority over topics that had been discussed before. But after my idea got rejected, most topics that did make that cut had been discussed many times before.
When I got a friendly email from the club that they were so sorry they couldn't use my topic, I was disappointed, but not just for the obvious reason. I thought that submitting my idea was a win-win situation: If my idea got picked, great! But if it didn't, I would have the rejection email as proof that my issue wasn't being taken seriously. I could print copies of that email and show them to everyone who didn't believe me. I could post those copies around the school to prove my point. But with an overly friendly email, anyone who read our correspondence would just think there was't enough room for my topic.
Regardless of why my idea was rejected, I learned that friendly form letters allow room for discrimination, because no one has to tell you why you weren't accepted. Not that it would be pleasant to receive a letter that you weren't accepted because of your sex, race, sexual orientation, or a number of other factors, but if you had that letter in your hands, you could expose it to the public. You could start a boycott against them or prevent other people from applying. But you can't do anything with a friendly rejection letter, even if you suspect that you were unfairly rejected. Maybe it would be better if our letters actually explained in a nice way why the applicant wasn't accepted. Then it'll be harder to reject someone without a legitimate reason. Then if you think your rejection wasn't right, you can fight back with the proof in your hands.