Maybe this should be the standard for every Christian, but it's certainly not the standard most American Christians now live by. Just as an example, most American Christians give little or nothing of their income. I can see why you'd say the standards were higher decades ago, but even then they didn't describe the way most American Christians lived. And even if it were, I'm not sure why you'd be opposed to calling people back to such standards. It's also worth pointing out that almost no Christians 50 years ago were living lives of radical devotion to God by quitting their jobs and moving to slums as you are implying Platt should do.
I also don't think it's particularly helpful to base your arguments based on your belief about how Platt is now, or should be, leading his life. We have a lot of writings by people who did those things you say you'd be impressed by, and who pleaded for the same things Platt challenges us to. Yet the whole church is not yet listening to those writings. I don't think we can fault Platt for adding his voice to the challenge, even if he hasn't arrived yet.