I felt the same way about some of the characters. They're all pretty much the same, but some of them (particularly Pinkie Pie in both episodes, and maybe a bit of Twilight) are starting to feel overplayed. I'm going to guess this has more to do with season 3 being the first season completely independent of the original creative director than some fanbase influence. The Studio B writing team is in full control now, and while they're great, trying to interpret characters created by someone else can lead to accidental caricature. Or maybe the Internet adrenaline is running off and we're starting to realize we're watching a show for 6 year olds.