Sin is basically a perversion of God’s natural order. In a specific sense, stuff like adultery, and homosexuality are sins. These are all perversions of God’s natural order. He didn’t create men and women to be promiscuous, He created them to have a relationship and sex(Gen 1:28 “Be fruitful and multiply”) within the order/confines of marriage which is between one man and one woman.
Jeremiah 32:27 says there’s NOTHING too hard for God so based on that He could easily change the rules. Why didn’t He change the rules? That’s a different story all together but Isaiah 55:8 says “For my thoughts are not your thoughts, neither are your ways my ways,” declares the LORD. God is a righteous judge and everything He does is perfect so I don’t even question Him about not “changing the rules” because I’m sure there’s a method to His “madness”.
You’re taking the “powerful” part of the verse too literally. What it’s basically saying is that because many of have accepted jesus as their savior, they’re made righteous and that God basically hears their prayers.
The things to consider about prayer and whether or not God answers it are what are our motives for asking and are we using wisdom in asking. If I’m broke, unemployed and bad with money, I’m not gonna pray to God to help me win the lotto and become a millionaire because that’s a unwise prayer. The smart thing to do would be to pray and ask God for the wisdom to manage your money correctly and to also ask God to help you find employment(while you also put in job applications).
Other things to consider is that maybe what we pray for isn’t the right thing for us, or that now isn’t the right time, or that God has something better in mind.