When it comes to the 50th, quite a few recent additions are to be considered as being for the 50th. They can't have 20 major projects all going at once and all opening/debuting the day the 50th celebration starts. For example, all the park entrances have had major work done. You don't want them all to be a war zone the weeks leading up to the 50th, and so, they were planned to be completed at least half a year before the 50th celebrations started.
Additionally, marketing will mention just about everything added in the past five years (e.g., Pandora) as part of the marketing campaign for those people who don't visit WDW regular like most of us do.
And when you go back that far as 'preparing for the 50th' there will be no shortage of things to tout: SWL, TSL, Pandora, TRON, Rat, gondola, all the resort rooms refurbed, FEA, the new night parade, etc...