I think that may have slightly something to do with it, but I think it's mainly Mike's policy of only presented finalized and complete music before moving forward, which is a bit ridiculous. These trend really did start with Jordan, case in point being the SDOIT overture and how the band decided to adopt it so quickly considering the fact that it was for the most part finished. And, perhaps Myung is a bit like myself and is afraid to push his own ideas forward especially when someone else gets so excited about it.
Is it all JR, no, but I think his arrival began the snowball that led to JMX's lack of input in the band's direction.