There is no clear answer. Perhaps it is because we desire autonomy in our life. Perhaps it is because we can see our everyday life more easily than we can eternity. Perhaps it is because we know we can't do anything for eternity, but think that we do have something to add to our own life.
Of course, none of these excuses hold any water. We must fight against the urge to handle everything ourselves. Our flesh cannot please the Lord. It requires us to go a step beyond. Hebrews 11:6 tells us simply,
"But without faith, it is impossible to please him because he that cometh to God must believe that He is and that He is a rewarder of them that diligently seek him."
If we can see so much of our everyday life, we should see that the Lord has wrought great miracles throughout it. He just doesn't save us and leave us to our own devices. No, he spends time creating a relationship and providing our every need. It may not always be what we want, it may not always be pleasant, but the Lord promises to preserve us unto his heavenly kingdom. 2 Timothy 4:18 says,
"The Lord shall deliver me from every evil work, and will preserve me unto his heavenly kingdom. To whom be glory for ever and ever. Amen."
I think we all honestly know deep down that the Lord's plans for our life will always be better than our own. I Corinthians 1:25 states,
"The foolishness of God is wiser than man; and the weakness of God is stronger than men."
For instance, this last fall, my God made a move in my life I never would have considered good. I had a very solid plan to attend Grove City College starting last year. Due to extraneous circumstances, I was unable to do that. At first, I was sad. And I was sad for a while. I grew over it soon enough and grew content to stay at home (for the most part). Then the Lord did things in my life here in Cincinnati that I doubt would ever have happened at Grove City. His plan regardless of how hopeless it initially looked to me was probably the best thing that's ever happened to me.
(Note: I would still recommend Grove City to anyone. The preceding paragraph should not be interpreted as bashing the college. It is a great school, but it wasn't the best option for me.)
So you see, this is why we should be so ready to live our life by Proverbs 3:5-6,
"Trust in the Lord with all your heart; and lean not unto thy own understanding. In all thy ways acknowledge Him, and He shall direct thy paths."