Rabbi Yisrael Yaacov Fischer (Shut “Even Yisrael” vol. 8 chapter 58) says this is done to avoid duplicating what was in the Mishkan. There is no need to presume non-Jewish influence.
This is simple to understand. I assume Rabbi Shach was against affixing square Luchos mainly because this was the Lubavitcher Rebbe’s idea… (Berachos 63a, התחיל הוא מטמא והם מטהרים).
Again, find Shut Even Yisrael here.