Ever since the ending in Mare do Well, I think RD's attitude has improved. She was just trying to be understanding towards Scootaloo, to show her that she did in fact care for her. I never did dislike Rainbow, I mean yeah she's cocky (exceptionally so in Mare do Well) but in reality she's prideful. She's not a bad person or anything, it's been shown many times that she cares for her friends. If anything, she just gets carried away with herself.