I have no idea what I think of Piper’s opinions in particular, but I do know that the way in which Evangelicals in general try to fix some things in the culture seems prone to create much friction, fission, and confusion.
There are a great many things a Christian man ought to be–more godly, a better family leader, more courageous, more productive, etc. And there are a great many things a Christian woman ought to be. Some of these things cannot be the same. A man can’t be a wife and he shouldn’t try. So there’s the difference.
But setting up templates and saying this is what a man should be strikes me as an attempt to use a mist as a focal point. If you are a man and want to be “Biblically masculine” then here is what you must do.
Trust in Jesus and obey Him. Period.
Did you get that? Good. Now you know everything you need to know. You don’t need to try to develop a universal description of masculinity. You don’t need to use the word “manly” in a certain percent of your conversations. You don’t have to go buy overpriced Davy Crocket outfits for your boys from Baptists “ministries” (you’re free to do so if you want, though I’d look for a secular version that is cheaper). Just trust and obey.
There are as many models of Christian masculinity as there are faithful Christian men. Every man who trusts in Jesus and obeys his commands is doing all he needs to do to “be a man.”
You see, real men don’t waste a minute of their time or any portion of their energy worrying about their manliness.