You have to remember that WAR pre-4.2 was a completely different beast to what it seems to be now, it wasn't always 'ungabunga press the funny button for X free fell cleaves and a side of fries'. People who liked that gameplay (cough) had to move elsewhere when it was removed. And then after they moved somewhere else, (like how I moved to DRK) THAT got 'ungabunga press funny button for X fell cleaves bloodspillers' too. Eventually, every job they move to loses it's 'spark' in this way, and then there's nowhere to jump ship to, so what then?

But yeh, we've already seen the level of simplification of 'current WAR' to 'press fell cleave over and over', that jump in complexity removal, occur already, when we went from 4.1 WAR to 4.2 WAR. If it happened again, people absolutely would quit over it. Not everyone enjoys gameplay that can be accomplished by those drinking bird toys. Maybe if tanks had actual tank responsibilities still like moving the boss and positioning it for good uptime during mechanics, it'd be at least slightly disguised, but what you suggest is even less of a rotation than Guardian Druid, and that's pretty dire for 'rotation complexity' as it is