Has the gospel message changed? Is the "modern gospel message" any different from the "old gospel message"? I think not. The gospel is the gospel. I think that was simply your way of disparaging me via ad hominem.
Now, show me where I said I was against open air preaching. And I can show you posts on this very board, addressed to you, where I tell you that I've participated in open air preaching. I am not against it at all. It's just not a very effective method of spreading the gospel. In open air preaching, I've seen a total of three people saved, and then never saw them again. Compare that to "cold knocking", where I've seen a couple dozen saved, and a few I was able to follow up with and see them churched and disciple. Then, compare that with the people that I've worked with, ate with, and was a good testimony to in my daily walk. Those that I've gotten to come to church using that method have a nearly 100% retention rate, versus the small percentage "cold knocking", and the zero percent while street preaching.
Given that the Great Commission is so much more than just delivering the gospel, which method should be used?
Now, more to the point of answering on topic, my objection is to the fact that street preaching drives people away more than it draws in. You yourself have admitted to having no fruit. If you have no fruit, perhaps you should look at your gardening method.
If I planted a garden, and nothing grew, I'd go to someone who has been successful in growing, and learn from them. After all, the Great Commission in Matthew 28 is very cut and dried. We are to do two things: teach, and baptize. Ironically, preaching isn't even on the list. If you are only out street preaching, you are failing to fulfill the Great Commission. The Great Commission is all about personal fruit.