The answer to this is going to differ heavily from religion to religion. You've already been inundated with the atheist and agnostic response. Christian theology could give you a few different answers.
The Bible could been seen as man's interpretation of God, therefore God's will is placed in terms we understand: emotions. Calling God jealous, angry, sorrowful, or joyful is a lot easier than asking you to understand a four-dimensional physical space. The latter is beyond your perception, much like understanding the "feelings" God exhibits, so it is simplified to terms you can understand.
The second potential answer would be: why wouldn't he/she be? You've made the assumption that emotions are bad or wrong, but if you throw out that assumption, there's nothing wrong with an emotional God. Maybe being "beyond that" is in fact a mistake? If he/she made us in his/her image, then of course we are given emotions similiar to God. Ultimately, who are you or I to judge whether such feelings are good or bad, or make a being imperfect?
Admittedly, I am deeply agnostic myself, because I ultimately don't buy any of the explanations I've provided here. But I've taken time and energy to understand Western theology, rather than dismiss it out of hand, and these are the explanations I suspect you are likliest to find.
Theology is not a belief in God. It is a study of the belief in God, the connection between humankind and the possibility of God, and the philosophies grounded in religious doctrine. Saying that trying to understand theology is a waste of time is the same as saying that trying to understand any social science is a waste of time.
You may dismiss the beliefs as "all made up", but their impact on our world is very real. Is studying politics a waste of time because it's "all made up"? Or are the arbitrary thoughts and feelings on how the world should be run suddenly more important because we've removed a belief that you personally disagree with?
Most theology is faith based and serves the purpose of dogmatically justifying and legitimising the religion in question. And all too often cover up the abuses. Of course I'm aware that there is also theology that follows a more scientific approach but if you go by the number of practitioners, that's surely a pretty small minority.
Ehh, I'm gonna push back and say that, as a lifelong atheist, I have greatly enjoyed reading books on Jesus and the early church. But I'm also a history nerd, so I enjoy stuff from other times already.
Religion is still dumb and makes people hate each other but the books are entertaining regardless.