1. I think the exact opposite is true. They're trying to keep a format that has more interaction and a slower critical turn. Sometimes they even need to ban things that just take too damn long
Sensei's Divining Top. By banning random combo pieces that pop up (with a gigantic card pool it's hard to tell both which combos will work and which are too hard to stop, some bannings from time to time are expected, unlike in Legacy where it is only their goal to keep degenerate combos from happening) they can keep it under control. Sometimes the combos just take too long for the average player to have a tournament either large or small scale work.
2. One could argue rotating bans keep the format dynamic and exciting. As a deck builder I was very happy to the possibilities that came from Bloodbraid Elf being banned.
3. The above two may also drive more players towards the format. SCG raising prices on Legacy staples does not mean that people are driven from Modern to Legacy, it means they're a business with the largest amount of money to throw around and create a collusive oligopoly. Without any evidence, you're trying to connect Legacy's raising prices to Modern dying?