It's like seeing Sheldon Cooper. In the beginning you wouldn't believe how "normal" he looks. He was a somewhat serious, quiet guy and a geek. He was funny because reacted to things around him in a slightly different way than others, because he's somewhat naive, he hates unnecessary interactions and superficial douches, he wants to apply his knowledge to situations that don't even need high intelligence, etc. Now he quacks catchphrases all the time and whines. He works at CalTech, for god's sake.

Peridot was a serious, cold, scientist who came to Earth. She pondered seriously about the things she saw (rain, towel, etc). The fun came from how she was unnecessarily obsessive, calculated, professional, and serious compared to the Crystal Gems. Which was why her line "I'm sorry I couldn't save you or the billions of other lifeforms who matter far, far less to me" was so moving. I get that she needs a break after her arc and Gem Drill and all, but some Peridot episodes feel like a comic strip drawn by a fan.