I don't think that is obtuse, exactly. I do think it can be difficult to interpret without proper tools. It isn't as simple to pick it up and fully understand it at the deepest levels as it is a work of contemporary fiction or biography. We have to remember that the Bible is composed of books the most recent of which were written nearly two millenia ago. This means that to get very deep into things we have to understand a little about the culture of the time, the political climate, how that passage or book uses earlier scriptures, its genre, etc. In that sense, it is inaccessible by someone who doesn't take the time to learn the basics about reading like that.

I think a big part of the problem when it comes to the Bible is American Protestant Christians have been encouraged to read the Bible on their own. "You don't need a pastor or priest to tell you about God's word, the Spirit will help you understand it yourself." I think that's a grave error that has cost Christianity more than it ever helped, despite the good intentions.

The Bible is a book for a community, and so it should be interpreted in community. It's similar to the experience of reading a book with a good book group: you glean insights and perspectives you would never have otherwise thought of had you read it yourself. This grows even more when you have educated people in your group, or people who've read it before, etc. The same for the Bible. It requires some education to really get down to what is meant in certain places. (I'm not saying someone can't pick it up and understand the words on the page, as if it's some secret cipher.)

A good example are Jesus' parables. How about the parable of the tenets for example. You could read that knowing nothing about Christianity or Judaism and "get something out of it." It could be about dishonest workers in that case, or the necessity of doing the job yourself.

Of course, this isn't what it's about at all. It's describing part of the reason God sent Jesus, because the tenants, the Jewish people, didn't bear the fruit they were supposed to. They didn't listen to Moses or the prophets, so God thought they'd listen to someone directly from the source. That didn't work, so God opens the door to the Gentiles entering the covenant community. It even quotes the Psalm to support the claim.

That may seem obvious to you or anyone who's been a Christian and read the Bible and heard the stories before, but you have to have some level of understanding to really get it. I don't think that means God is being misleading, only just like everything else in life, the more you study something the more you understand it.

If a deity were to write a book about how to live one's life, wouldn't it make more sense to make it as straightforward as possible?

First, I think many people over many centuries wrote, compiled, and edited the Bible. Yes, I think God guided them, but it still contains their personal idioms, idiosyncracies, and concerns.

Secondly, I don't think the Bible is primarily about "how to live." The Bible is intended to be a story. It's the story about God and creation, and just like any good story it has intrigue, history, love, hate, revenge, sacrifice, suffering, hope, faith, despair, and a lot of mystery.

Of course, there are parts that are law codes, there are letters that do contain some manual-like information about how to live, but most of the "how to live" is learned through reading and re-reading the stories and embracing the God in the texts, learning from the mistakes of the people before, etc.

Learning how to live from the Bible happens the same way you learn to live in real life, only its through the lives and stories of others, rather than your own. You slowly change and grow, for better and worse, by the people you associate with, the media you create and consume, the shared history of your family, people, city, country, and unique place in history. This teaches you how to live, although it doesn't do so propositionally. It happens as your habits of living are shaped by these events and histories.

The Bible is the same way. As you learn about God through his interactions with his people, the exciting stories and the boring laws and everything else, it slowly shapes you into a different person, if you let it. And it can do a much better job if you read it with other people who are different than you, but who share a belief in the love and power of this God.

We all know that even if God wrote a "one hundred tenets to living the successful life" that no one would follow it anyhow. I'm pretty sure the stories of the Bible itself plus simply a cursory look at human history would tell us that.

I know this is long, but I don't really see how to answer a deep question like that very simply.