I swear they're addicted to feature creep at this point.
Fishing minigame. Unless we're pulling up mermaids and nymphs and naiads and sirens what is this doing in an H-game?
Sure, it's great that they're getting better at programming and so on but, again, making a porn game. They can make what they want, but the players want more options to fuck the harem or, failing that, plot advancement, because once the plot's advanced far enough maybe some event will occur so [insert favorite character here] will become fuckable. And once the main plot's finished then theoretically Gabe will get back to more side stuff with the ladies.
Nope! Fishing minigame.
Maybe, maybe, there'll be a new category of achievement that unlocks some really useful item (that isn't itself related to fishing). Maybe you have to fish up one of the legendaries, or one of the Dragons of the Nine. Maybe Bal'Rana gets really horny fishing, I don't fuckin' know. More likely: Gabe, as they say in their blog posts, just really wanted to add fishing to the games since the beginning.
Though this does remind me of a narrative comedic podcast I listened to, where an arts reporter is excited (read: horny) that she gets to interview this really famous and brilliant furniture designer...but it turns out his real passion is fly fishing and all his far out designs are just things that make fishing more convenient for him. After a moment of confusion, she says, "Okay, I can work with this..."