Or HaChaim on Genesis 11:1/אור החיים על בראשית י״א:א׳

1 ויהי כל הארץ שפה אחת. The whole earth had a single language. We must give some thought to the intent of the generation that built the Tower. What exactly did they mean to achieve by means of a city and a tower? If all they had in mind was to give expression to some aspect of heresy, how was that expressed by their building plans? If indeed their heresy was of a serious nature, their punishment, i.e. scattering them over the globe, seems an inadequate punishment. How would that punishment cure them of their heresy? The words ועתה לא יבצר מהם כל אשר יזמו לעשות, "Must not everything they are planning to do be withheld from them now?," are difficult. This line poses severe problems for a believer. Why did they say: "we will build a city for ourselves?" Who else was there to build a city for? Besides, did not G'd want mankind to construct a civilised universe? Surely He did not want a bunch of cave-dwellers?

2If we accept the view of the sages that G'd intended one third of the earth to be under cultivation and civilisation, one third desert, and one third water, if you were to line up all the cities side by side even now several thousand years later, they would not cover one hundredth of a third of the available land mass! Most of the earth would remain desert, or at least uninhabited! It seems therefore that the roads linking one town or village to another are all considered as part of the "built up" areas that are to form approximately one third of the earth's surface. When the Torah reports that the people spoke one language and דברים אחדים, were of one mind about all important issues, the meaning is that they literally congregated together without spreading out at all. To prevent becoming scattered they built a single city. They built the tower as a landmark so that if anyone of them strayed too far from home he would be able to orient himself by seeing the tower from a distance. The "name" the Torah speaks of is the "name" of the tower, i.e. its visibility from afar, its significance. It was this very reluctance to comply with G'd's intention to populate various parts of the earth which annoyed G'd. Had they not been endowed with free choice, they never could have defied G'd's plan for an evenly populated earth in this manner. G'd therefore had to resort to some stratagem to frustrate their plan without interfering with their basic freedom of choice. G'd achieved this by confusing their uniform language. Henceforth people who had a language in common would tend to congregate together, and as a result of a common language they would choose to live together. This could only be accomplished through their migrating from what used to be a central location, or what we are fond of calling "the cradle of civilisation." G'd's whole purpose was to fill the earth with people. The sin of wanting to remain together in one location was almost as serious as outright heresy, being מקצץ הנטיעות. While it is true that there are numerous mystical angles to this episode, and our sages elaborate on many of them, none of these explanations represent the plain meaning of the text.