Without trying to insult anyone at all, I'd say no, not everyone is able to.
With that said, I don't think all are actively trying to. I think many folks really wanna just have a near copy of what would have come with the games they own, and that's perfectly fine.
There are some really talented folks here, and you can watch a lot of em get better with every cover. When I look at some of the really old covers I've downloaded from the site versus stuff from users like Segamer, Wolf, Larry, and many others, I'm blown away. And of course the work from the vets is always top notch. Shenske is still cranking out amazing quality work after 6 years of doing it. Some of this stuff is hands down BETTER than the original while replicating it to the last detail.
Now if we could just get more of you guys to start using Illustrator or some other vector-based soft...