The idea has been brought up multiple times before and rejected for the above reasons. As for my stance, I propose a skin downloader to be added eventually but with different qualities as mentioned. First off, skins wouldn't be automatically downloaded; that's ridiculous and could cause players to wait a long time while skins download. If possible, a preview of the skin without downloading it would be nice but I'm not sure that's possible without just downloading it... With regards to inappropriate skins (aka, taking your eye virginity away), you take that risk each time you download a non-official map. The mapper could append pornographic material and you wouldn't have a clue until your arrive in the map. But if it's anything to consider, I've never seen a map like that in my life and I've been around since 0.3.4. And as for invisible skins and skins with bad dimensions, that can easily be taken care of with a nifty in game skin delete function. As soon as you download a skin you down like, delete it. To be honest, I don't know what unaimable skins are so I have no comment on that. ^^'
Here's an idea to help player's have less hassle. When accounts are in place, a function can be added with the skin downloader to rate skins. Player can view ratings when they consider downloading another player's skin. It would go like this: Player A has a new skin and player B downloads it then rates it 4 stars. Player C see's player B's 4 star rated skin by viewing "skin information" (which I guess can be viewed on player B's profile, if programed that way) and disides to download it and rate it 5 stars. To everyone else, player A, B, or C's skin rating has 4.5 and the cycle goes on and on. I'm not sure how this information would be kept, since I'm clueless at coding, but it seems like a good idea to me.
Give others the respect you wish to be respected with. In the mean time, enjoy the website!