Better use of home screen real estate on devices with bigger screens. This is particularly true on the bigger iPads where it's absolutely crazy that a 12.9" iPad Pro has the same 6 x 4 icon grid layout as on an 8.3" iPad Mini. I want as many of my apps accessible with a single touch without needing to click into a folder so bigger screens having more icon slots would actually give me extra benefit from those bigger devices. This gets even more important now that the home screens also support widgets because once you've added a few widgets (or even only 1 or 2 on an iPhone home screen) you've taken out quite a few icon slots so restricted even further the number of free slots on your home screen available to quickly launch your most used apps.
Apple has even gone backwards on this with iPad. With I think it was iOS 14 on an iPad you could set the left-side widget pane to always be on screen so you could get 3 or 4 double-width widgets permanently displayed on the left side of the home page and still have the 6 x 4 icon grid to use for apps and on my 10.x" iPad that didn't look at all cramped to me. Apple removed that always-visible option for the left-side widget pane in I think iOS 15 so now we are back to just that 6 x 4 icon grid (plus the dock of course) that I consider over-spaced even on the regular10.x inch iPads and on my current 12.9" iPad Pro a 6 x 4 icon grid is just absurdly over-spaced for the available screen size.
I also have the same issues of what I consider to be inefficient/lazy home screen layout on my iPhone 14 Pro Max. That search box at the bottom takes pretty much an entire row of extra potential icons. Surely Apple could rejig things slightly, come up with a less screen-space-intensive way to quickly launch search, and as a result give the user the option to have an extra 4 icon slots on their home screen. They could even offer a full-width 1 x 4 icon search widget so for users that really hated whatever alternative tap target Apple offered to get to search quickly those users could simply add that search widget across the newly created 7th row of icons to make the home screen look like it does now.
Not optimising home screen layout for different screen sizes just seems to me to be laziness on Apple's part and it robs those of us who have paid for devices with bigger screens of one of the potential benefits we could have from that buying decision.