God did promise the land of Canaan to Abraham. For example God says to Abram (Abraham) in Genesis 17:8:
The whole land of Canaan, where you now reside as a foreigner, I will
give as an everlasting possession to you and your descendants after
you; and I will be their God.
However, a few verses earlier, God said that Abraham would be "the father of many nations":
Abram fell facedown, and God said to him, "As for me, this is my
covenant with you: You will be the father of many nations. No longer
will you be called Abram; your name will be Abraham, for I have made
you a father of many nations. I will make you very fruitful; I will
make nations of you, and kings will come from you." (Genesis 17:3-6)
Israel (another name for Jacob) was only one of those nations. It would not give due respect to Abraham, the father of many nations, to name only one of those nations after him. For a chart of the nations descended from Abraham based on the names of his descendants in the Bible, see The Genealogy of Abraham.
Isaac was the father of two nations, the Israelites and the Edomites, so the land of Israel could not be named after him, either.
Jacob, or Israel, was the father of a single nation composed of twelve tribes. In the Bible story, that nation conquered and adopted as its homeland Canaan and the transjordan valley. So his name is applied to that nation rather than the name of Abraham or Isaac.
According to the biblical story, later, when that nation began to fall away from faithfulness to God, it broke up into two kingdoms, Judah and Israel, each of which acted as a separate nation. However, the promise to the Patriarchs--Abraham, Isaac, and Jacob--is seen as fulfilled in the reign of King David, under whom a unified nation of Israel reached its greatest extent.