This is the point, the “why” of which “has never been made particularly clear”. Its necessity is simply asserted, not substantiated.
Why is God unable to create beings that are immediately able to “love, trust, and obey God”?
I would also point out that the relationship between “disobedience and/or suffering” and “of learning to love, trust, and obey God” is likewise asserted not substantiated (and what I have seen in the past has generally been far more of a thin rationalisation for the existence of suffering, than a compelling explanation of its necessity).
Addendum: do Christians who fail to suffer sufficiently during their lifetime, or fail to disobey sufficiently, fail to get into heaven?
Further addendum: what about children who have died too young to suffer or disobey at all?
And if God cannot create, directly, what this world can, then we are again left with the not-unreasonable conclusion that God is not omnipotent.