What is the importance of reading the Bible?

Psalm 1:2 [NIV]

"Blessed is the one who does not walk in step with the wicked or stand in the way that sinners take or sit in the company of mockers, but whose delight is in the law of the Lord, and who meditates on his law day and night."

Joshua 1:8 [ESV]

This Book of the Law shall not depart from your mouth, but you shall meditate on it day and night, so that you may be careful to do according to all that is written in it. For then you will make your way prosperous, and then you will have good success.

Your question was answered by Luke in the book of Acts of the Apostles:

Acts 17:10 and 11 King James translation

And the brethren immediately sent away Paul and Silas by night unto Berea: who coming thither went into the synagogue of the Jews. These were more noble than those in Thessalonica, in that they received the word with all readiness of mind, and searched the scriptures daily, whether those things were so.

Even the most dedicated of pastors, have been known to misinterpret Scripture, and unless we allow the Holy Spirit to be our teacher, we cannot be sure that the messages we receive concerning the Scriptures is what God wants us to learn from them.

Having been pastored by many Good Ministers in my life, almost every one will at some point give a sermon on Act 17:11 and the point of message invariably is to seek the truth in what you are receiving.

It has been my experience that the Holy Spirit will give you the meaning from the Scriptures, which you need at the time, and may have you understand them differently under differing circumstance.

Jesus himself said;

John 14:26 But the Comforter, which is the Holy Ghost, whom the Father will send in my name, he shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you.

John 15:26 But when the Comforter is come, whom I will send unto you from the Father, even the Spirit of truth, which proceedeth from the Father, he shall testify of me:

Pastors according to Merriam Webster:

PASTOR, n. [L. from pasco, pastum, to feed.]

    1. A shepherd; one that has the care of flocks and herds.

    2. A minister of the gospel who has the charge of a church and 
    congregation, whose duty is to watch over the people of his charge, 
    and instruct them in the sacred doctrines of the christian religion.

Remember what Jesus said to Peter:

John 21:15 through 17

So when they had dined, Jesus saith to Simon Peter, Simon, son of Jonas, lovest thou me more than these? He saith unto him, Yea, Lord; thou knowest that I love thee. He saith unto him, Feed my lambs. He saith to him again the second time, Simon, son of Jonas, lovest thou me? He saith unto him, Yea, Lord; thou knowest that I love thee. He saith unto him, Feed my sheep. He saith unto him the third time, Simon, son of Jonas, lovest thou me? Peter was grieved because he said unto him the third time, Lovest thou me? And he said unto him, Lord, thou knowest all things; thou knowest that I love thee. Jesus saith unto him, Feed my sheep.

Any farmer knows that he can put his livestock out to pasture, but even though his pasture is full of vegatation the animals will seek out the best grass to eat and ignore the weeds. And if God gives animals that need for that which will be the best for them should he expect less of us?

One of the reasons I enjoy this site, and visit it each day is that through some of the questions and answers I have found that even at 76 years old having been a Christian for 63 of those years I still have a lot to learn about God's love for us.

This is a question that is addressed in various places in the Catechism of the Catholic Church:

The Church "forcefully and specifically exhorts all the Christian faithful. . . to learn the surpassing knowledge of Jesus Christ, by frequent reading of the divine Scriptures. Ignorance of the Scriptures is ignorance of Christ. (133)

"The Sacred Scriptures contain the Word of God and, because they are inspired, they are truly the Word of God" (134)

"The Church has always venerated the divine Scriptures as she venerated the Body of the Lord" (DV 21): both nourish and govern the whole Christian life. "Your word is a lamp to my feet and a light to my path" (Ps 119:105; cf. Is 50:4). (141)

Reading Sacred Scripture, praying the Liturgy of the Hours and the Our Father - every sincere act of worship or devotion revives the spirit of conversion and repentance within us and contributes to the forgiveness of our sins. (1437)

The Christian family is a communion of persons, a sign and image of the communion of the Father and the Son in the Holy Spirit. In the procreation and education of children it reflects the Father's work of creation. It is called to partake of the prayer and sacrifice of Christ. Daily prayer and the reading of the Word of God strengthen it in charity. (2205)

The Church "forcefully and specially exhorts all the Christian faithful . . . to learn 'the surpassing knowledge of Jesus Christ' (Phil 3:8) by frequent reading of the divine Scriptures. . . . Let them remember, however, that prayer should accompany the reading of Sacred Scripture, so that a dialogue takes place between God and man. (2653)

So, from a Catholic point of view, reading the Sacred Scriptures is a central means of encountering God and taking part in the mystery of salvation, leading to repentance and the forgiveness of sins, as well as being a guide for a life of Christian charity. Ideally, reading the Scriptures is an integral part of a Christian devotional life, along with the sacraments and other forms of prayer.

The Sadducees posted a question on Christianity.SE about married life after resurrection (they didn't believe in resurrection of the dead) and Jesus replied (Matthew 22:29):

But Jesus answered them, “You are wrong, because you know neither the Scriptures nor the power of God.

Reading the bible == knowing the scriptures helps us to prevent developing erroneous views that hinder our spiritual growth or potentially lead us astray. Sometimes even preachers from the pulpit preach doctrines that have errors or even heresies in them and though the preachers responsibility is greater, the listener is not without one.