no, they haven't. the majority of her PV's are still high quality.
my different thoughts on the PV's you mentioned
:
Microphone - unique, creative, exciting. it has that "wow" factor to me. i've watched it so many times.
Sunrise and Sunset - pretty boring.
MOON - beautiful and creative. it really made me want to cry. one of my favorite PV's.
Lady Dynamite - we get to see the fun ayu who loves to have a blast and not take herself seriously all the time. i love it!