Faith is a relationship.
Religion is taking what should be a good relationship and turning it into a bureaucracy.(something Jesus was strongly against)
Even though Jesus states in this text not to use meaningless repetition, this is one of the most commonly repeated prayers there is.1“Beware of practicing your righteousness before men to be noticed by them; otherwise you have no reward with your Father who is in heaven.
2“So when you give to the poor, do not sound a trumpet before you, as the hypocrites do in the synagogues and in the streets, so that they may be honored by men. Truly I say to you, they have their reward in full. 3“But when you give to the poor, do not let your left hand know what your right hand is doing, 4so that your giving will be in secret; and your Father who sees what is done in secret will reward you.
5“When you pray, you are not to be like the hypocrites; for they love to stand and pray in the synagogues and on the street corners so that they may be seen by men. Truly I say to you, they have their reward in full. 6“But you, when you pray, go into your inner room, close your door and pray to your Father who is in secret, and your Father who sees what is done in secret will reward you.
7“And when you are praying, do not use meaningless repetition as the Gentiles do, for they suppose that they will be heard for their many words. 8“So do not be like them; for your Father knows what you need before you ask Him.
9“Pray, then, in this way:
‘Our Father who is in heaven,
Hallowed be Your name.
10‘Your kingdom come.
Your will be done,
On earth as it is in heaven.
11‘Give us this day our daily bread.
12‘And forgive us our debts, as we also have forgiven our debtors.
13‘And do not lead us into temptation, but deliver us from evil. [For Yours is the kingdom and the power and the glory forever. Amen.’]
14“For if you forgive others for their transgressions, your heavenly Father will also forgive you.
15“But if you do not forgive others, then your Father will not forgive your transgressions.
Instead it should be an example or template, for the basics of prayer.
seeking His will,
demonstrating that you are following His wishes.
Faith (not religion) is an interesting thing.
Contrary to popular belief there is only one correct interpretation of who God is and what he wants, and even amongst the few who will admit this as truth, even fewer will admit that they do not know it.
I don't believe any human can know exactly what is right, but it is our responsibility to seek and to come as close as we are able during our lifetimes.
The answer to your question,
"Why should I pray for forgiveness?"
You shouldn't have to. You should want to.
If you have a relationship with someone, then your desire should be to strengthen that relationship and make them happy.
If you hurt a friend or spouse, etc.... you do what you can to mend that tear in the relationship.
If you have a relationship with God, then you will want to do the same.
Sin hurts God, so when you sin while in a relationship with God, you will wish to seek his forgiveness.
If you do not have a relationship, they why would you care?
Why are people jerks on the Internet? Because of their anonymity and lack of relationship. (just for comparison)
There is truth, and we all seek it in our way, even those who claim not to are trying to define it in their lack of definition.
Of course my interpretation can not be 100% correct either because I am human, but this is how I understand it from what I have read and studied.
Waiting for your deathbed, is in essence trusting that a bureaucracy will compensate for your lack of a relationship.