There aren't many more single new features that are going to justify upgrading that will exist on the mobile platform. Apple is playing a game where they try to add enough features to prevent the upgrade cycle from becoming too long. Encourage people with 2 or 3 year old phones to upgrade this cycle instead of delaying a generation.
Honestly, Apple's business model is harder if everyone wants to upgrade to a certain new version. The M1 Macs were so good, everyone upgraded their Intel Macs and then mac sales dropped. It's better logistically if the sales are more predictable and consistent year-to-year.