You're right on one point; we'll never be perfect in this life. But does that mean we ought to sit back and do nothing about our bad habits, or other things we do wrong? No, of course not.
One reason we need to be concerned about what you call our "shortcomings" is because they have an impact on others. If I'm selfish and unconcerned about the needs of others, they will be hurt. If I habitually lie and cheat, others will be hurt. If I ignore my social responsibilities or act immorally, others will be hurt. As the Bible says, "None of us lives for ourselves alone" (Romans 14:7).
But we'll also end up hurting ourselves. Bad habits always have bad consequences -- always. It may not be obvious at first; in fact, we may deceive ourselves into thinking we're on the right road. But we aren't. The Bible is clear: "You may be sure that your sin will find you out" (Numbers 32:23).
We should never be content to "accept ourselves just as we are" (as you put it). But God does accept us just as we are! He knows all about us, including our sins and our failures -- and yet He still loves us and wants to come into our lives to forgive us and change us. And this can happen to you, as you turn to Jesus Christ and invite Him into your life. I urge you to make your decision for Christ today.