I believe this is an obvious case which shows that the Scribus default for displaying images is incorrect.
I think it would be fair to say that the "average" user would assume that Scribus would show their images as they would see them in any image viewer software. In other words, they would assume that the image shown would not be "modified" in any way.
Scribus, out-of-the-box, does not display all images in the way that the average user would expect. Instead, it defaults to displaying images at what it calls "normal resolution" which doesn't always display the image at its best quality. (And what does "normal" mean? To me, "normal" means "as is", or "real" rather than what Scribus seems to think it is.)
This means that a user who doesn't know that Scribus has different preview resolutions - and that's probably most users as the "feature" is hidden away - could, quite easily, assume that Scribus is broken or can't handle images properly.
Example Case: User has a nice high-quality 300dpi image. They put it in an image frame. The image is all blurred and looks awful. They try zooming and various other things but it still looks awful. They conclude that the software is useless for this kind of thing. They move to different software. Scribus looks bad and they tell their friends to steer clear of it.
Fonts would - by default - never be shown blurred or modified in some way by default, so why are some images shown this way? It doesn't make sense to me.
It makes me wonder how many software reviewers have come across this "feature", without knowing it was a "feature" and just dismissed Scribus as a product that doesn't work properly and given it a bad review accordingly. People don't have time to delve deep into the documentation so find out that the software does something differently to what they would expect, especially when it's something as simple as just displaying an image.
To cut a long story short - too late? - in my opinion, Scribus should - out-of-the-box and by default - show images at the best resolution that it can and then it's up the the user to change things if they want to. Displaying things as they are should not be an option, it should be the default.