I wouldn't say it's treated as a detriment, it used to be CnP wasn't allowed full stop and a 75% freehand minimum requirement was in force before I become the reviewer then moderator for this section. So in todays standards we're quite lenient as we allow CnP to be approved although it's moderation rating will be low as textures are first and foremost a piece of art created by an artist and as such we wish to "reward" or recognise when someone makes a texture/skin that is of particularly high artistic merit. By that same token CnP doesn't require much time or effort at all and so is moderated based on that understanding.
I suppose what I'm trying to say is that I think you should give freehand artwork a try, I do my own works using a mouse so it doesn't even require expensive equipment and in GIMP which is free software.
Mr.Goblin's Tutorial! this is also probably one of the best tutorials on how to get started with it
EDIT: Also when you say "you've rated everything except the quality of the artwork." you are correct as it isn't your artwork and has been copy and pasted from elsewhere. You yourself say this is "niche" which means it doesn't qualify for a Simply/Useful rating since U/S implies the skin has a broader usage or usefulness to the community.
By the way, I'm glad you've made this comment as I think discussions about the moderation, the standards of the site etc are all really useful to the community and to other users. I'm always open to making changes, however I think those changes need to be based on the underlying rationale's that we accept.