1. Ensuring that Iraq didn't have much in the way of explosives-delivery capacity left, be it tanks, plane, missiles or anything else, and therefore ...
2. ... Iraq had no real way to resist being overrun by tanks.
Now, for a variety of reasons, the decision was made NOT to entirely overrun Iraq with tanks. But the whole point was that we could have.
In Gulf War 2, however, we learned of the acute difference between overrunning Iraq and running it. Both air power and tanks turned out to be much more useful for the former than the latter.