But yes, I agree it’s not the right choice for me and many others who want to have full ownership over our data, and they should make that clear in advance.
The whole point of Signal is you have full ownership of your data. You said you can transfer the data to another device, right? I get that inability to export cleanly is an annoying bug, but technically you have full control over your data the whole time. It seems to me that it's easier to guarantee no one else can get your data (at the expense of data export friction), than it is to provide "do anything you might want with your data" while still guaranteeing privacy.