Because adding Jesus' name to a request is like saying "please" when you're a little kid. It's the magic word.
Shame on us for trying to rub the lamp for the Jesus genie. Asking for something in Jesus' name bears far heavier implications than saying "please" when you want a chocolate chip cookie. Jesus' name invokes power, authority, and sacrifice. When I align myself with Jesus, I bear the responsibility of Romans 12:1-2 and Philippians 2--I must humble myself like Jesus did and become a living sacrifice. I must say "Not my will, but Thine be done." That's what Jesus' name means.
Jesus stands in the gap for us before the Father and intercedes for our requests. He reminds the Father that this lowly human (me)--this follower of Christ who's struggling in finances or relationships--has been pardoned from her great guilt by Jesus' own personal payment. This human likeness of Christ I aspire to have lets me stand before a holy God and ask for help, which God promises to give me because of Jesus' love and pain. If I am truly a replica of Jesus--if I can stand as a "little Christ" (i.e.. Christian)--then I will want God's will, whatever that looks like. I will not subvert God's will, reinterpret God's will, or manipulate God's will so I triumph emotionally, financially, physically, or socially.
Because if I'm like Jesus, I'm walking a path of suffering, and I'm leaning into God's strength for wisdom, courage, and destiny. God's will is my will. That's what I'm asking for. That's what I want. In Jesus' name.
“The prevailing idea seems to be, that I come to God and ask Him for something that I want, and that I expect Him to give that which I have asked. . . . This popular belief reduces God to a servant, our servant: doing our bidding, performing our pleasure, granting our desires.”—A. W. Pink, The Sovereignty of God