In the early seasons, her voice was not as idiosyncratic like it was in the later seasons. I didn't notice it until now.
shareshe looks a bit different also, and they didn't make her as stupid lol
shareThat's what always happens. Take a stupid character and make them stupider as the show goes on. It happened with Chelsea on That's So Raven, London on The Suite Life of Zack and Cody, and so on. I even found this list online of this phenomenon: http://tvtropes.org/pmwiki/pmwiki.php/TookALevelInDumbass/Live-ActionTV
I've always found it annoying. The characters start out relatively normal and then they become the village idiot.
I realized why they do that. They want to go different directions with a show and they take that popular wacky character and make them a caricature of themselves to try and appease the fans.
For example Spencer on iCarly. I'm sorry but Cat's change has nothing on what they did with Spencer. They wanted to take iCarly in a more mature teenage direction and since Sam was a major part of those changes they choose Spencer. Spencer was a wacky guy in the first 3 seasons but he was serious, a good role model, and a stable brother/father figure. Season 4 they threw that all out the window and brought Gibby in as a main character and in my opinion that was to keep the younger viewers entertained. He pretty much became a living cartoon character and him and Gibby became a slapstick duo. Luckily they realized it was a horrible choice and scaled him back to a lot and he got back his best qualities by the last season but they made me dislike his character a lot of the time during that middle period.