I think accuracy comes down to what you want the prop or costume for. It's been discussed a lot on here about prop accuracy and I think the same holds for costumes. A lot of people want a representation of what the item would look like in the SW Universe. Other people want a representation of the prop.
I guess I'd fall in the category of wanting a representation of what something would look like "in universe". However I'd buy an armor kit if it was less.
I agree.
I get prop replicas because I love the fictional universes that exist within the films, and I want objects that I can imagine actually came from that universe. I'd rather have a prop replica that reflects the intent of the creator of that universe, than one that reflects the limited time, skill, and budget of our real universe. Call it playing make-believe if you like.
If all other factors were equal, I'd take a replica that is cleaned up, smooth metal that lights up and makes sound, over a lumpy, hurriedly-painted piece of resin with untrimmed mold lines and halves that don't line up quite right, that purports to be more similar to a screen-used prop.
Of course, all other factors are rarely equal, so my actual purchasing/constructing decisions will depend on things like cost, time, effort, and availability.
As for screen-used props, I would definitely love to get my hands on some of those! But for a different reason: screen-used props are an artifact of the creation of the film itself. It's like the pickaxe Hillary took to the top of Everest. It was one small tool that played a part in achieving something great. For that reason, I wouldn't care how messed up or poorly made a screen-used prop is. But I'd be getting it for a different reason than I'd be getting a replica.
The realities of filmmaking include limited time, money, and necessity. It is common for a film director to approve props and costumes that aren't perfect, even when he would like them to be perfect, because any professional filmmaker knows that taking the time and effort to do things "perfectly" cost more than doing things that will be "good enough." Especially when the director knows that he's not planning to linger on that prop in close-up. When you first saw Star Wars in the theatre, you probably didn't notice that the stormtrooper's helmet was asymmetrical. Lucas knew you wouldn't notice. So he would have been right not to care.
Back when Star Wars was being made, VCRs were not that common, and DVDs weren't even invented yet. He didn't make movies for people to watch in hi-def, frame by frame. He made them to be seen in the theatre. Even today, while directors are mindful of the popularity of blu-ray, their primary focus is on the normal viewing experience.
And it's not as though the craftsmen and artisans who make the props don't care about what they do. But when your boss hands you a list of tasks and a deadline, you don't show up at the deadline with half of your tasks incomplete because you were taking extra time to make everything "perfect."
If you want to argue that asymmetrical stormtrooper helmets were Lucas' intent because he approved them that way, well, he also approved the symmetrical MR helmets, which he knew would be scrutinized up close.