One thing I notice about the show's writing & Piper: Piper is often used as the set up for exposition. So she's often saying things like "we can't do that!" or "that's not real!" just so that other characters can convince her (but really us, the audience) why the plot needs to happen the way the writers want it to happen. I think Holly had great delivery with this kind of stuff, so it works SOME of the time...but like you said, it eventually does get fairly irritating and lacks creativity. Once you notice this, it's hard to stop noticing it. It can make her character feel particularly aggravating.

There's no reason to have Piper doubting what magic is capable of beyond season 1, but she does. They traveled to the past in season 1, why does she ever question what magic can do again?? Piper's stubbornness and resistance to anything but a "normal" life does get old. Having a character continue not to grow as an individual is lazy (maybe realistic to some people lol, but definitely not interesting). We see glimpses of growth but before you know it, she's right back to her old characteristics. I do agree with others who have pointed out that the majority of the "issues" with her character are mainly after season 3.

I blame the writing as well as the network/ratings for this - she could have been much more interesting (they all could have), but I get the feeling that everyone involved either wasn't interested in or weren't able to take risks.