If getting people "out of hell" and "into heaven" were all there was to it, and if "quality" was somehow optional for the process, then I could see your point. But you set up a false dichotomy by saying since we can't get perfection, we shouldn't bother trying to get better.
The Great Commission does not command us to "go ye therefore and make converts of all nations". It commands us to make disciples. Disciples do more than learn how to make more converts. If your theology teaches that Christians shouldn't "polish the brass on a sinking ship", you probably discount or avoid other ship-related disciplines as hull & sail repair, mastering sea-sickness, and simple navigation. What good is it to ask people to repent and convert, and not prepare them for how to live afterwards?
The gospel's content is more than just "get out of jail free" instructions, and the proper response is more than the empty-headed repetition of a prayer. There is far more that the Church is called to do for it's members than to just to be "seeker-sensitive" and count converts.
"Two philosophies guide my ministry. One: quality is more important than quantity. God calls us to make disciples, not converts. Principle two: Principle one is just barely true. Quantity is also important. Truth is, quality and quantity normally go together. Christian Schwarz has done extensive study into this, surveying 4.2 million church goers in 1000 churches in 35 contenants. The verdict is clear. Quality churches are nearly always growing churches. People like to go to high quality churches."----Rick Warren
"Simply stated, we are to make disciples, not converts. This means we have the responsibility to consciously do things that will result in new Christians growing toward spiritual maturity."---Rick Warren
"The church is in the sending business. It is our goal that eventually 25 percent of our membership will do some kind of mission project each year. I'd love to see our attendance go down every summer, not because people are on vacation but because they are out on the mission field serving. Another goal is to send out 200 career missionaries from Saddleback in the next twenty years." We as the church of Jesus are called to makes disciples not converts, (Matthew 28:19). We are not to try to see how many we can get to respond to an altar call. We are to see how many we can make into active, viable members of the body of Jesus Christ. We must bridge the gap and make disciples of the Lord Jesus and not followers of " -- insert your name or some ministers name here -- " ministries. We are not to build the kingdom of ourselves. We are to daily crucify our flesh; pride, greed, lust, apathy, etc.… not exalt ourselves and follow Jesus and lead men and women into personal intimate relationship with Jesus that they might become followers of our Master, Lord and Savior Jesus."-----Rick Warren