Yes, you have a point with the thrill, but if you think about it like that it would be even more of a thrill to wait till it ends since everybody is talking about it and shiz. Oh and another reason why I dislike watching on-going anime is because usually I tend to forget what happens in the previous episode, especially if I start another series and watch them in parallel (as I would have to since I'm not going to only watch an episode a week).