A new opening for each episode is of a truth daring. The amount of time,effort and money put into that is like a proof to the audience that yes,we know what we're doing here. Animes/shows aren't like books in which their covers don't really matter(atleast for me). It's the opening that draws the attention of the audience. Like hell's paradise,apart from it being a normal shonen anime,I really loved the opening song. Lest I forget,music matters too. Unique opening, wonderful music equals to glorious anime.
Well yes, in anime its "cover" matters a lot. I almost always like music regardless of anime, but when the visuals are so creative that they drive me crazy, that's where they really have me.