I think that a campaign world should change over time. However, I am not a big fan of lots of world-shaking cataclysms, or the PCs as mere spectators for major events. I think that a campaign setting should evolve somewhat over a few years, and metaplot is good when it helps the GM come up with adventure ideas and when it lends verisimilitude to the setting.
I think that supplements advancing the timeline by a year or two is good, as it can help the DM determine what has changed in the rest of the world while the PCs have been adventuring (perhaps hostilities between two countries have erupted into a war that the PCs might be interested in fighting in or taking advantage of, maybe the old king died under mysterious circumstances and there is now a succession war or nobles trying to break away from the kingdom, or any number of other things). Including changes that took place in adventures published for the game line or even better changes that result from the adventures, are very helpful, even if the DM may need to alter things a bit based on how his/her players completed the adventure.
That said, a campaign world does not need to change through new published material. It is perfectly fine for the DM to pick whatever starting point they like, and just make changes as the players move along. However, I think that even then the DM should have things that happen as time passes so that the players see that the world is a real place and not a static thing. For example, if the players hear about a dragon taking over a trade pass, and do nothing about it, they should hear about the repercussions taking place.