First, Luke having his right hand cut off was for a lot more than just to end that fight by having Vader literally disarm him. It was also to create a connection to Vader since Vader also lost his right hand, thus showing a parallel between Vader and Luke, a "the sins of the father pass to his son" thing. This revelation is clarified when Vader has his right hand cut off by Luke in Return of the Jedi when Luke momentarily went to the Dark Side fighting Vader, and seeing how he was becoming Vader snapped him out of it.
Second, so what you're saying is that for the loss of a limb to mean anything the person who lost the limb has to be an invalid for the rest of their life? And if they get a prosthetic arm that allows them to do what they could before then the loss of their arm means nothing to them? You clearly don't know anything about the loss of a limb and the affect it can have on people.
Maybe I'm getting my "Star Wars" wrong, but didn't Vader lose his hand to Luke only in the next movie? (If it happened also in the prequel Jar-Jar-Binks "Star Wars" trilogy I wouldn't likely recall it.) And wasn't that hand loss pretty much the same situation, only now with the tables turned- Vader taken out of the fight and forced to accept Luke's offer to come to the... erm... "Light Side of the Force?" Which he ultimately did. We don't know at the Luke hand-loss point that Vader will also lose his. But regardless, you see my point: it wasn't just to "add" a li'l story to Luke, now the Guy with the Neat Mechanical Hand. It served a specific narrative purpose.
And, no, obviously I'm not saying that anyone who loses a limb must be an invalid forever (though apart from artificial limbs IRL it will be a permanent loss) for it to have impacted their lives. I'm saying that the writers didn't have the Inq lose her/his arm with the same level of impact as the cosmetic fashion scars we can add to our Inq's faces at the CC. If Luke's (or Vader's for that matter) hand loss served only to show father-son continuity- or only served to take either one out of the fight- or only served to show thematically whether the Dark or Light side of the Force was winning at one point or another... the main thing is that it served a purpose. The removal of the Inq's arm served zero purpose if in DA4 we're up and running again because it didn't affect the Inq's story in any other way if it's not permanent. The most it did was make for an armless couple cutscenes at the end of Trespasser- i.e., completely superficial.
As to some emotional impact of having once lost a limb- i.e., but now not at all since everything's back to normal and hunky dory- I'm sure there would be some- more or less. But what would that entail? A scene at the beginning of DA4 where the Inq says, "Gosh, that temporary arm loss was awful"? Practically the arm loss would've had zero impact. It would be fully restored, carry on as per usual. I'm pretty sure I can say unequivocally that those who've actually lost limbs would love the opportunity to have their limbs fully restored and be able to take them for granted again, would, if they had the means, go to any kind of lengths to have the limb restored. But part of what makes their story compelling is that they can't. It's not a quaint story of "ain't that special." It's a gripping story with, yes, emotional impact. I work in industry, so believe me, I know these stories. Safety videos don't let us forget them, and there was one series by a guy completely disfigured by an accident (of his own doing) at a petroleum plant who nevertheless made his living afterward by making safety videos and giving related safety lectures to employees. But, no, I haven't experienced it myself (thank good fortune and my own sense of personal safety), and, like anyone who still has their limbs, I thus don't know exactly what it's like. I don't mind.
In the Inq's case, however- you know, in a fantasy realm where magic happens- if he/she can restore the limb, it sorta brushes aside/ side-steps/ ignores/ glosses over the real sense of loss that people who've lost limbs endure. It takes the easy road. Or do you think that the Inq with a fully restored limb would really know what it means to permanently lose a limb or be forced to use prosthetics? They wouldn't either... cuz magic. Which is the actual point I was making: that the Inq's arm loss meant something because it had an actual, practical, miserable, but meaningful impact. Now imagine the opening scene of DA4 in which the Inq as cameo demonstrates what it means to them that they've permanently lost a limb. Even, "I don't want to talk about it," would be meaningful.
And this brings it back to the central question: if the arm loss meant anything to the Inq's story, what did it mean? Are the writers to sorta say, "Oops, no, our bad, it's all better now" for DA4? Or are we to learn to accept our handicapped Inq as they now are who- whether they wanted to or not- lost a limb in order to save the world? Do we merely pity them for it and curse those nasty DA writers or feel a profound sense of our DAI character's role in the unfolding events of Thedas that continue to call for new heroes to make yet new sacrifices? Mind you, the Warden could've made the "ultimate sacrifice" and in any case was (so we figured) permanently plagued by the taint, unable to have children and living a drastically foreshortened life. Thanks for the heads-up, Duncan!