Why not?

It’s something that benefits both Android and Apple users by removing unnecessary restrictions.

Because Airdrop is miles more reliable and easier to use than anything Android came up with (yes I am aware of QuickShare, it sucks)?

Because having two walled gardens where people need the same third party app to move data between them is silly?

Because Apple needs some “see regulators! we are not a monopoly, we are cooperating with Google :D” wins.

Because with all the upcoming restrictions to Android, many are saying they might as well move to the nicer of walled gardens. They’re trying to reduce reasons for people to think those thoughts.