I've seen this asked a number of times and I want to weigh in (again...)
Affinity is TERRIFIC - GREAT JOB!!! I so very much want to adopt this as my primary image-editing tool. I've figured out how to do almost everything I need in terms of image editing.
For me, however, this is a serious flaw in an otherwise FANTASTIC piece of software. The clumsy "export" procedure is pretty much a deal-breaker for me. I work with lots of files & create a lot of derived files using "save as" in the *other* tool. I've been trying to make the switch, but when I need to crank out some work I can't bring myself to open Affinity for this very reason.
I do understand that the intended workflow is to stay in Affinity format until the end, then export. Unfortunately that simply does not fit the way I work. Although this seems tangential to the *important* functionality of the tool, for me it's a big road-block.
Just to be clear, the behavior I'm hoping for (like many other applications) is this: Open a file in any supported format - "Save" does just that, saves the file in the original format, in the original folder; "Save As" saves the file in the original folder, with a choice of format. A warning that the desired format does not support all the features of the working copy is fine, with a single-click "OK" to proceed.
I'm not sure from your response if there is an intent to change this - I do hope so.