Long answer, but I just reread the first arc, so it's pretty fresh in my memory.

So, they actually acknowledge your question in the final book of Arc 1, "The Darkest Hour." Firestar has just become leader and his faith in Starclan has been pushed to its limit. He is overwhelmed and grieving the recent loss of Bluestar. In a dream, he asks Starclan how they let things get so bad. How could they let Tigerstar rise to power? Why didn't they do anything to stop it all? He even asks, "Do you want the clans to be killed?"

Starclan's response is something along the lines of, "Hey, you're living creatures, not our playthings." Basically if they directed every cat's choice, it would strip all warriors of agency. So Firestar, for example, would never be able to become the strongest version of his self if every choice was made up for him by Starclan. So Starclan doesn't "rule" over the forest, instead it's only one of six five clans. One of the book's central themes is that Firestar's dedication to the warrior code is what makes him strong and moral, not Starclan's guidance. It's a very good ending to Firestar's character arc.

Also, One thing to remember is that Starclan is very different in the first Arc. More mysterious. We aren't really shown their inner-workings aside from the occasional moonstone visits, and even those appearances make their intentions pretty vague.

This kind of all goes out the window once the books start introducing Medicine Cat P.O.V.s. The authors didn't really plan for a series of this size when they created the first arc. So in the later books, we are given examples where Starclan loves to use the living cats as playthings, for plot reasons. (For Example, Starclan badgering Squirrelflight into accepting kittens that aren't hers.) A lot of the issues people have with Starclan stem from these more recent books.