LITTLE FLOWERS OF SAINT FRANCIS OF ASSISI, Chapter 36
HOW ST FRANCIS EXPLAINED TO BROTHER LEO A BEAUTIFUL VISION THAT HE HAD SEEN
I think it's pretty clear that the main point we're supposed to take away with us from this story is the importance of poverty. But poverty is something more than just not having the things of this world, it's not needing them. The vow of poverty is just promising not to acquire the things of this world. The gift of poverty is being okay with that. One with a true calling for the monastic life takes this vow because he sees that he will find no happiness in acquiring the things of this world.
One tenet of Buddhism is, we achieve nirvana when we extinguish all desires. Apparently, from the Christian perspective, this extinguishing of all desires seems to be the same idea as the gift of poverty. These two belief systems can't be completely harmonized. It's just my opinion, but to me it seems we can't extinguish all desires by our own efforts. The gift of poverty is just that - a gift - from God. We follow our path by God's grace and mercy.