I have rereead my source And it was not 100% accurate. First it was not the director but the writer of the show(it was in the book Sailormoon crystal released before the serie)
the writer of the serie wanted to expand the storyline, but someone higher than him said him "no, it's forbidden, just follow the manga"
but we don't don't from who came the order. Naoko or Toei Producers, but we can assume it's Naoko because he also confirmed that most of the change in the season one storyline from the manga were Naoko decisions(the Shinetto not ying the same way and being in love with the inner shenshi in the past)
But the Director made comment in an interview prior to the show that Toei animation and Naoko were forced to accept thing from the other party, (
For the original Director, he was not really a bad Director, he was just not suited for Sailormoon, most of his work was One Piece and he had nearly no experience in shojo manga(except few ep on Precure)
It's like Naoki Tate in Dragonball Super, Naoki Tate is an excellent animator but he worked nearly only on One Piece sinc 5 years, his animation style just don't fit to Dragonball, it's not what people awaited
Chiaki Kon was just the most suited people in Toei animation to work on sailor moon, I have talked about her work on Higurashi but she also know for good shojo Romance and some of the best shonen ai serie(and she even worked on a Shojo ai) and have also some experience on Precure. Magical girl/Shojo romance/homosexual relationship/some horror strange element, it's just the recipe of Sailormoon