I think there are three different aspects that come into play here:
Missing Features
First, I strongly believe a lot of the need for undated reminders stems from the fact that Agenda doesn’t allow you to make the type of overviews yet that you currently use Reminders for. From our end we have to look ahead and think where we’re taking Agenda, which also means that we don’t want to add functionality that later could lead to a lot confusion about how things are supposed to work when certain workflows now compete with others.
For example, we very consciously don’t allow you to assign reminders to notes (only to text) and vice versa, don’t allow you to assign events to text (only to notes). Yes, there are cases to be made about assigning events to a specific paragraph, but it would add UI, bloat the app, and most of all make the whole events-linked-to-notes concept a lot more confusing for many, especially novice, users.
Here it’s a bit the same. For us, the difference between an undated reminder and a checklist item is very very thin. The current reason for having undated reminders, as far as I can deduce from those requesting it, is mainly because the reminders app would give them an easy overview of all those checklist items that are currently important. However, there are other ways to achieve this, for example by adding a specific tag to the checklist items like “priority” and creating a smart overview for this tag. Now this is not the same because you can’t see yet a list of just that checklist item and the overviews are showing the entire note, I get that. But this will change, so once we introduce the ability to make overviews that show only unchecked items from a checklist for example, especially in combination with tags or other search parameters, we see the need to go to the reminders app diminish even further.
Presentation
As you and Drew already highlight, users have different workflows and would like to show things in different ways. For example, should undated reminders and/or overdue reminders show in the calendar in the inspector? And on all future days or just today? Is it ok for undated reminders to only appear inside notes, without the ability to get to these in the calendar etc. Sorting out these workflows and implementing these is not something that can just be added in an afternoon (especially given the technical limitations under the hood, see below). Just to say that it’s often not so much a difference of opinion but rather a matter of priority. And with that in mind, we prefer for example to prioritise the kind of note filtering and search enhancements mentioned above that have a lot more added value beyond just reminders for everyone.
Performance
You are not convinced there’s a performance argument, but as I explained in your other post life is not that simple alas. I also wouldn’t expect it to be a big issue, but alas Apple provides us with very few options and if you’d like to get the reminders that are undated you basically have to fetch all reminders a user has, and that includes the completed ones. You might not have many reminders that are not checked off yet and have a nice compact list in the Reminders app, but heavy Reminders app users might easily have hundreds of completed reminders that we would all have to fetch. Not saying it’s impossible, but it’s certainly not trivial to make this work smoothly for all.
Hope this gives more insights. As Drew says, don’t get me wrong, we very much appreciate your feedback and the detailed description of your thoughts and workflows. It might sometimes feel that we just dismiss things, but that’s certainly not the case. It really helps to shape the improvements and changes we make and to identify the workflows we might miss or could better address, so thank you for that!