"It's easier to ask for forgiveness than permission." While there is a ring of truth to that statement as it may be practiced in the world, it would be a tragic mistake to apply such a cynical philosophy to our spiritual relationship with God.
Psalm 50 is largely about acceptable sacrifices. The Psalmist recognizes that God does not "need' sacrifices, as if He were hungry or thirsty (vs. 12-13). Nor does He need us to supply any lack on His part. Everything in the world is already His (vs. 10-11).
While offering sacrifices to God is a good and positive thing, we should not mistake that we are doing God any favors. Verses 16-21 demonstrate that God is looking at our hearts, not just at what is in our hands, when we sacrifice. If we don't live in accordance with God's law, our sacrifice isn't meaningful or acceptable.
When our children were little, we often encouraged them to say, "I'm sorry" or "Thank you" when appropriate. Those words are important - but we also listened to the tone in which they were said. Offering sacrifices to God is an important part of our spiritual walk, but for OUR benefit, not for HIS. We are the ones who need to sacrifice rather than God being the One who needs our sacrifice.
Finally, we must always strive to remember what we are saying by our sacrifice. We must be genuine, and offer out of gratitude or penitence or love or appreciation. To have an impure motivation such as trying to "buy our forgiveness" or offer a spiritual bribe or "make up" for breaking God's laws - well, that's not going to get us anywhere.
With God, it is not easier to crassly ask for forgiveness than permission.