Why does "Looking forward to"imply positive anticipation for something?
Language happens doesn't it? Â Somehow 'looking daggers' doesn't mean please hand me the carving knife.
My guess is that it's not so much the "forward" as the "looking" that suggests positive anticipation.
Looking forward to X ...
Looking implies searching, anticipating, awaiting, longing. For example: Looking for a win by the Packers this Thursday.
Negative anticipation is usually obvious from context. For example: Looking forward to a tax bill in the mail this week.