Is Steem-Bounty is More Interesting and Effective Giveaway or Rewarding System ????
Yes it is. You already describe in your post.
But when there were many winners in a contest or arranging game , the hold arranger give them in many times. But using #steem-bounty , contest holders can easily give his rewarding amount by clicking his vote.
Another thing a small SP holder like me can give reward to the commenters on my post. My vote value is very low and I can only give them dust vote. So I normally set a steem-bounty on my post.