Honestly there is nothing wrong with releasing 100,000 butterflies at your wedding ceremony and there is nothing wrong with including tissue paper in your wedding invitation.
But to me, they sort of fall into the same category - unnecessary, maybe a bit showy, and certainly a matter of taste.
Either one alone wouldn't affect how I felt about a person. So from most people I wouldn't even notice the tissue paper. But a lot of little things do add up, so if it was an invitation from someone who often did things of that nature, I might roll my eyes a bit and think "typical so-and-so".
My graduation announcements (years and years ago - pre-facebook even!) came with the tissue paper. I thought it was useless then and didn't use it. I saved it for