One of the authorities of the salaf (the early generation of the Muslims) said: "It has reached me that the meaning of this verse is: I have not created you because I have a need for you, I have only created you so that you may ask Me, so I will forgive you and give you what you ask." [Tafsir al-Qurtubi]
Al-Sadi writes: "Allah has informed us that He neither cares, nor concerns Himself except with these people (the believers), and that, were it not for your dua to Him - the dua of worship and the dua of asking - the He would not care about you nor love you."
So were it not for the fact that mankind makes dua to Allah, Allah would not care about creation. This fact, in and itself, is sufficient to make a person realise the importance of dua.
"Dua: The Weapon of th Believer" - Abu Ammaar Yasir Qadhi, pp. 45, 46