If it would have been God’s foremost intention to just save the world, while minimizing human suffering, he would have done it right away after the fall. Instead of waiting 4000 years until sending Jesus down to us. Or, if there is some reason for these 4000 years that is unknown to us, God could have made this time easier for humanity. For example, by introducing some kind of sedative drug and supplying food by miracles, so that people would have been spared from all this self-inflicted suffering.
And likewise, if God’s foremost intention today would be to bring this world to an end after having saved it through Jesus, the Last Day would long have come and / or God would help with all available miraculous power in missionizing the world. Or if there is some reason unknown to us why it did not come so far, the proposal with the sedative drugs applies again.
And likewise, if God would desire to make the life of his children as bearable and simple as possible, he would: (1) talk to us more directly and more often, (2) completely change our character in supernatural ways, (3) tell us what situation we are in at every point of time, and why.
Yet, all the above is not the case. Means God seems to have also some other intention with this world than just “closing it down with the lowest possible damage”, to then proceed in heaven where everything is great. But what could be that intention?
That intention can not be to let people earn rewards. Because according to the doctrine of grace, every reward for human behavior is neglible compared to the undeserved donation of grace.
Might it be that God “is so deistic” because his intention is still what he had in mind when creating this world? Which would be, as far as we understand it, to have human beings as “his image”. As something that is pleasing to look at. So maybe he enjoys just looking at this world (or currently rather, tries to). Which would be indeed an activity that would make God appear to us as largely “deistic”, compared to how he could potentially behave to us, in all his power.
So perhaps this world is something like a table decoration in God’s living room, so to speak? Note that this comparison is meant to illustrate how unfathomable huge God is, not to call Jesus’ work for us something small. It is huge thing because Jesus did it in the shell and with the limitations of a human being – doing it as an all-powerful God would be no big thing indeed.