Copy pasting good work (and providing useful LINK) from people that could contribute to a place isn't that bad imo, just know where to post such things and where to avoid, but if I see a good thing on twitter or somewhere, then I rather copy paste + provide a link then turn around the words and make it something of my own...
To find something that could lead to an interesting discussion isn't that bad imo, when I do such things I also only do it where its appreciated...
Sometimes the posted thing could be a question as well, just to know how other respecter members thinking about that matter, so isn't it better to post it like that with a link rather then making it up yourself?
Copy pasting for a sake of starting a discussion and adding your view is much different then the just copy paste image and put source link.
If forum allows this then their lot of user that just paste image/text and put source underneath. Mods always delete this post when reported.
Allowing these post will just flood bitcointalk from all kind of information from outside without any discussion happening in this forum.
But you will be always welcome to discuss the news/outside information if you really have to add something in it.