Ok, imagine Loki saying this in the movie.
"Why am i in a glass prison? Is my beauty so utterly intense that you cant fathom it being blocked behind bars?"
And Thor's like
"We need to keep an eye on you at all times brother. We can't take any chances."
And Loki just says
"No brother, you are all unable to live without the sight of my overwhelmingly fabulous face."
http://www.screeninsults.com/images/silence-of-the-lambs-cell-middle.JPG
"Why am i in a glass prison? Is my beauty so utterly intense that you cant fathom it being blocked behind bars?"
And Thor's like
"We need to keep an eye on you at all times brother. We can't take any chances."
And Loki just says
"No brother, you are all unable to live without the sight of my overwhelmingly fabulous face."