This hasn't been suggested and discussed 1,000,000,000,000,000,000,000,000,000,000,00010 before.
Seriously though, 4J knows we want it and they've even said themselves it's something they want as well. However, in game development, there is a fair bit of politics. Especially with a game like Minecraft. It's essentially at the whim of 3 companies. Microsoft might want one thing, Mojang another, and 4J something else.
I agree as well! other arcade games like trials evolution has a track editor that has the option to upload to a share file within the game and anyone can view/ download to play for themselfs. It cant be that hard to impliment the same feature into minecraft.
I think that 4J won't do it because the game is rated E for everyone. Some worlds would have adult content in them.
Hence why every single video game that has any sort of online interaction states...
Online Interactions Not Rated by the ESRB
There being adult or mature content on maps would not stop them from adding a map sharing feature. If parents didn't want there kids to see that sort of thing, then they should be more proactive with their child when they're playing Minecraft.
I REALLY wish The game had the ability to copy save files. If your playing an adventure/ pvp map that you made and you want to save your progress, then you have to save all the crap that your players have added to it. If you could copy the map, you could have a clean copy and a running copy at the same time. If you wanted to start over you could delete the second copy and replace it with a new one.
Under the current circumstances you can only share your map with friends one time. Unless its an arcade game, like spleef, but then you have to drop your players every time you reset. There's no way to share a modified pvp map more than one time because you can't make copies.
I don't have the software that allows you to upload xbox files onto the web, that might work, but should i really need to download a god damn third party software and use a flashdrive just to play on the xbox!!????