Well then let's put it this way: what DPI did you scan & save your covers at? Because the covers for Army of Two (both of them), Fable II, Skate 2 and Borderlands that I just downloaded from your Imgur link ended up on my hard drive as 72 dpi.
Here is a link which will illustrate the difference in quality between an image that is 72 dpi and the same image that is 300 dpi. Most of us strive for higher quality 300 dpi (minimum) cover images because it just plain looks better on a printed, final product.
Imgur is a quick, simple, free service that processes extremely large volumes of images. Most people just want to get an image up fast and turn around and re-share it fast. Concerns over image quality is a secondary concern for Imgur's usual clientele, and in the case of hastily-posted memes and gifs of cats, the fact that the image is there at all is good enough for most people. Imgur compresses the image quality to give itself an easier time in the long run.
As an example of what happened, take a look at this.
This is a Sonic Adventure cover that has been sized for DVD cases, straight from this website.This is the exact same cover, saved to my hard drive and re-uploaded to Imgur.At first glance, they seem identical in quality. So I saved a copy of the Imgur file to my desktop and compared the file properties of the two files.
As you can see, the two files now have different dpi values, and the only thing I did was upload it to Imgur. But just to further illustrate, here is a direct example of how this degrades the image quality:
Feel free to open those images at full size and compare them for yourself. The top image shows the original file straight from TCP. The bottom one is the Imgur copy. Notice the artifacting around the text on the cover's spine, and especially around the Dreamcast logo. Imperfections like that will most certainly show up when you print the image, which is why we strive for 300 dpi covers. If you're going to the trouble to print out a replacement cover in the first place, why not make it look as nice as you can?
Also, all of the covers in your Imgur link are also different sizes. Most cover creators try to keep the finished images a uniform pixel size per physical media format so that every cover fits into their cases the same way every time. Most DVD case covers here are 3225 x 2156, though not everyone agrees on cover dimensions all the time. Just try to make sure that your covers are uniformly-sized and, more importantly, that the finished product fits into a case properly in the end.
