Most Anime, wither or not it has mature themes or is 'corny', is aimed at the 13-18 year old Japanese TV viewing/Manga reading market.
The different themes and stories just appeal to different types of those viewers and some are written by authors who want to also write to 'larger' audiances as well. But make no mistake, they also have to mostly pull in the 13-18 year old crowd. From GitS to Pita Ten, they all have that market somewhat in mind, if not clearly targetted. The only ones that don't are the 'kiddy' shows and even those still have some of them watching.
Their Mangas on the other hand might not be.