I have never played any sims game with story progression on. I play with aging off, and no sims in the world die if I can help it. If I want a sim to be in a particular situation, I switch households, play that household until I get the outcome I want, and then go back to my main family. I have played that way for so many years that I would be very unhappy to change my style of play.
To me, playing "my way" IS the sims. I am guessing a lot of players feel that way. I think if EA does not voluntarily offer us a toggle to turn off story progression, they are likely to get hounded until they do.
That being said, I know a segment of players really want a changing world, so I am glad EA will be offering the option. As long as it remains an option ....