Partly it's because when stuff's new, it's exciting. If we went back to a few years ago, I'm sure we'd see all that stuff and think it was boring, because then everything was fresh and new, even when it was fresh and new and bad.
All these things go through phases. Look at the world of movies, where there're often a few slow years and then a few bursting years. But the world of startups is much newer and much younger, and so we haven't gotten used to these cycles yet.