From a sociological standpoint, Morris is probably on to something. Mind you, it's patronizing insofar as you have many Baptists who have thoughtful, principled reasons for opposing paedobaptism. So his analysis borders on a hasty generalization.
But that caveat aside, he's probably right that for many evangelical Americans, opposition to paedobaptism is influenced by a revivalist paradigm. And I share his aversion to decisional evangelism.
However, even though I myself am a tepid paedobaptist, his analysis is one-sided. To begin with, decisional evangelism represents a travesty of conversion. But we shouldn't judge the principle by the travesty.
Moreover, we need to compare and contrast that to the opposite error. The 18C evangelical revival was a heaven-sent reaction to the dead formalism of liturgical churches. If decisional evangelism is bad, so is the presumption that your child is saved because a minister sprinkled water on its head. Many people are only too happy to seek spiritual shortcuts and vest false assurance in religious ceremonies. Ironically, the revivalism of Finney and Graham is just a different kind of ritualism, replacing baptism with the sacrament of the altar call.
The basic problem is taking a cookie-cutter approach to everyone. But everyone doesn't have the same experience. On the one hand, some people are devout, lifelong Christians. They were Christian for as long as they can remember. For them, there was never a conscious transition. And there couldn't be, since it was real to them as soon as they had the cognitive development to reflect on it.
On the other hand, you have nominal Christians. Some of them lose their hereditary faith. Others assume they are Christian just because they grew up in church.
A good pastor needs to preach an evangelistic sermon every so often. Take nothing for granted.