The reason why I do it is because I have never heard of it before, it is called Limbo of the Infants for a reason.
And nobody ever heard of Limbo of Infants until about the year 1100 either. This is speculative theology, and occasionally a speculator gets it right. Obviously we can't force you to believe it, but never having heard of it before is about as weak an argument as you can get. Make a theological argument as to why it's impossible or somehow contrary to Catholic teaching, and I'm all ears.
You also have to realize that the biggest reason that people oppose Catholic EENS teaching is that they have this monolithic view of hell, where Judas and Joe Stalin are suffering the exact same fate as a kind-hearted Jєωιѕн grandmother who sacrificed her life for her children. People recoil at the injustice of such a thing. But that is due to a false notion regarding hell. Several of the quotes you cited in fact explicitly teach that people suffer in different degrees in hell. There isn't just a single cauldron of fire that everyone just gets indiscriminately tossed into ... whether you spent your entire life as a serial killer or you just slipped up one time, fell into a single mortal sin, and died. God is perfectly just, and that kind of thing is preposterous ... and it's contrary to Church teaching. In fact, one of the dogmatic EENS definitions taught the variability of eternal suffering, so it's actually heresy to deny this. So the biggest objection to EENS dogma is in fact based on a heretical premise.
Also, another quote cited from St. Thomas teaches that there is no injustice in depriving ANY human being of the beatific vision, because it's something beyond our nature. St. Gregory nαzιanzen actually called this out in his rejection of BoD (differentiating between punishment and glory, saying that lack of punishment does not equate to receiving glory ... = beatific vision). So if some unbaptized infant dies and doesn't have the beatific vision, it's no injustice and in fact causes them no suffering or even pain of loss. They enter the proverbial "happy hunting ground" where they can enjoy perfect NATURAL happiness for eternity. This notion that an unbaptized infant is hurled into a burning cauldron of fire is also implicitly behind why so many people try to speculate about how they can be "saved". People don't understand that there isn't this simple BINARY proposition at work, that you either go to heaven and experience perfect bliss for all eternity or go to hell and suffer unimaginable torments for all of eternity. There's a huge range in between. Infants in Limbo experience a perfect state of bliss and happiness, to the greatest extent that nature allows. Imagine living without pain or suffering or sadness or sorrow, but rather having the greatest happiness possible IN THIS LIFE, and that's basically what their eternity is like. So those unbaptized aborted children are in fact "saved" from hell, even if they don't attain to the beatific vision.
I also posit that there are people who do not attain the beatific vision who suffer very little for all eternity.
Here's the way I look at heaven, hell, eternity. Everybody gets to go wherever they want. So, for instance, I myself love to pray and love spending time in church. There are others, however, who can't stand it and even if forced to go are checking the second-hand on their watch constantly. They would rather be out partying. So for them, prayer causes them to suffer. There are those who, like myself, love classical music. There are others for whom listening to classical music is torture; they need to shut the stuff off and turn on the rock music. So imagine that heaven is like praying in church and listening to classical music. That is bliss for those who have the dispositions to enjoy these things, but it's sheer torture and torment for those who have developed a repugnance towards it. That's the difference between heaven and hell also. For some the knowledge and presence of God and eternal truth is sheer bliss and delight, but for others it's torture (similar to how I described classical music). So we spent our lives developing our sensitivities with regard to how we shall experience the reality of God, with it either giving us pleasure or extreme pain. And it will cause greater pleasure for those more disposed to them, and greater pain the less disposed one is to them. So an evil genocidal serial killer will be tortured by the goodness of God more than a generally-kind person who tried to do his best his entire life.
If people properly understood the nature of heaven (the beatific vision) along with the happiness and suffering associated with one's eternal fate, there would be less repugnance towards Catholic EENS dogma.
PEOPLE HAVE A FALSE NATURAL UNDERSTANDING OF HEAVEN ... and that is a root cause of EENS denial. Heaven is not simply a place of NATURAL happiness, but rather the undeserved free gift of the beatific vision that is not necessary for the perfection and perfect happiness of human nature. This is a key teaching of St. Thomas. Heaven is an unmerited ELEVATION of human nature. So I don't necessarily believe that the American Indians, for instance, in their belief in a happy hunting ground after death were necessarily all that mistaken. I believe that such a thing, or close to such a thing, is attainable by people through the practice of natural virtue. But they can NEVER see God as He is and attain to the beatific vision without the Sacrament of Baptism and membership in the Church.