Yes, I would agree that if our present time period is just like all other previous time periods of the past then the doctrine of a shut door of heaven is unnecessarily cruel. But if we have truly entered into the Day of Judgment itself, and God indeed began to pour out His wrath upon unsaved mankind on the date of May 21, 2011, continuing until now, then the doctrine of a spiritual judgment in which God has shut the door of heaven and ended His salvation program as a means of pouring out His wrath---is about as mild and gentle of a day of wrath upon evil men as is possible to imagine.
Yet all kinds of people criticize this teaching of the Bible laying out God's righteous judgment program and proclaim it to be "heartless,” and "cold," and "unrighteous," etc., etc.
Many of them, all the while proclaiming the idea that God shut the door on May 21, 2011 as cold and heartless, themselves believe that God will one day cast all sinners into the pit of hell and burn them up forever while they consciously endure that awful eternal suffering.
The only way someone could say this present Judgment Day scenario is cruel and heartless, is by not recognizing nor believing that we have entered into the final judgment of mankind. They think it’s cruel and heartless because, in their blindness, they think they are still living their lives exactly as past generations of people have lived their lives, far from the evil day.
Sorry to tell you this, but you are not living on the earth in any normal period of time. At this time, and for several years now, you have been living on the earth in the Day of Judgment. The Day of God's wrath is occurring all around you. In your world. In your country. In your state. In your city. In your town. In your own house. This is the evil day. Once you truly realize that, then you'll be able to see how kind and merciful and good and gentle the Great God of the Bible is –even as He punishes mankind and finally makes them pay for their sins.