I can only speak for myself and my family. The RDL was the final straw (amongst many other issues) which led me to the Holy Orthodox Church. It was intolerable for me and my wife...especially the gender neutral language.
Fair enough, but as you say, it was the final straw, not necessarily the biggest one. I'm sure you had bigger underlying motivations for coming over to Orthodoxy.
Also, I have experienced Byzantine chant, Znamenny, and Russian choral....I like them all better than Prostopinije. Znamenny is my favorite. But that is just my opinion.
A few years ago I would probably have said the same thing. Prostopinije has grown on me- the more I explore it, the more i love it. That said, prostopinije is actually a form of znamenny, and a lot of the melodies are very close or the same, but there are fewer of the very complicated melodies you sometimes see in znamenny.