@timo I'm coming from DayOne so that's what I'm use to. Forgive me if I'm comparing the products.
With DayOne on iOS, I can start a journal entry today, or any day for that matter, and when a photo is added, the program will ask the user if they'd like to change the entry to the date contained in the photo metadata. I believe it will also auto-date an entry if you start in photos, and use the share-sheet to share into DayOne.
Where I find this most useful is for pulling photos into my journal entries from old photos. I see your point as well when you say the photos are already shown in the day when adding an entry, but I've found it much easier the other way around. Perhaps I've just gotten use to that from YEARS of using DayOne as my main journaling app.
I've just imported almost 6000 entires today. I'm going back through and cleaning a few things up. Thanks for your hard work and consideration, and obvious care you put into your work!