Well, paxx, the only problem with uploading the file as a seperate upload would be that if there was a major major update in the skin, then people who may be searching around on the site, and come across the old one, might not know there's a new one, and then they'd have the old version that apparently had something wrong with it.
No, not a good idea at all.
And I have to agree with pinchecl on the topic of comments. If only more people would comment on skins

I dont think there's really any reasonable way to force users to comment on skins, however

but he is right that download counts really aren't terribly important (or at least they shouldn't be to the best of the skinners out there).
But I guess it's whatever helps you as an artist improve your skills. Be it download numbers determining you to work harder, or comments influencing you to change one thing about your technique to the other. It's all in the eye of the designer