The game's got a lot of systems that just exist(and repeat), with no further point to them so far, and which thus could legitimately be seen as filler.
But, this is like saying that the free-roam/shooting system in GTA is a filler because it has no further point but just to send you to the next story cutscene.
The reason for having guild management, fishing, mining, finishing contracts and foraging goes with the lore and ROLE of being a random guy who ended up in a poor town and was called a "Hero".
They all have different tiers, zones, and upgrades for the player to feel like the "Hero" is being better and better in his job of putting the town on the map again.
And, the reason there is WAY too much stuff to do is not for you to do ALL of them, but to focus on one you like.
One can complete the entire game just by doing and upgrading their management and foraging perks, in case you hate fishing and mining.
Another user can complete the entire game doing only fishing and not even grabbing an apple in the entire playthrough.
Even, if someone doesn't like fishing, you can get EXP doing stuff like foraging, and then spend the extra levels on fishing perks so the work is easier, in case they need something for this last "minigame".
That is the "ROLE" element I want the game to have, that's why I put lots of effort into giving the player lots of different ways to progress the game.
Again, they are all systems to integrate you into the world and, ALSO, because HHG is a
little bit of a management game, and the reward of doing all that job is, in long-term goals; leveling up the girls and seeing further in their story or just a short-term goal like, for example, just getting a new fishing rod so the minigame is easier.
I understand there are some people who don't like the minigames and all, and just want to progress in the story. That's where the cheat codes enter.
Whenever the game is finished, I will probably do an AVN version inside the own game, for those users that want to read and read and read without any pauses.
But, if you don't like the little management the game has, or you hate the idea of spending time with the girls to "level them up". Then it's simple; This game is not for you! And that's completely fine!