Jesus didn't say, "Ask, and if I feel like it, I'll give", or "Seek, and if I'm in the mood, you'll find".
He spoke in the declarative. This is not about a fickle God, playing favorites. This is a powerful reassurance to those who petition Father God . . . assurance that when they pray, when they seek, when they knock, He responds. And responds with good things. Always.
It's me, with my expectations and limitations, that doesn't see, doesn't recognize, doesn't follow God's leading into the amazing things that He has planned for me. He gives. Good things.