“‘Then [with a deep longing] you will seek Me and require Me [as a vital necessity] and [you will] find Me when you search for Me with all your heart'”
I’ll be completely honest about the fact I have only learned one reason why God leaves us in an imperfect state. He wants us to be dependent on him. This can actually be found in the AMP (amplified) version of Jeremiah 29:13. I recommend reading the amplified version of the Bible because it explains further what is being said.
God wants us to “seek [him]” with “a deep longing” and “require [him] as a vital necessity,” or need him, and “search for [him] with all [our] heart,” as said in Jeremiah 29:13.