API are secure only if you can secure the authentication details. A modified app (be it as something modified and distributed on a unsanctioned channel, or custom injected by another malicious actor/app) can easily siphon out your authentication tokens to a third party unbeknownst to you the user. However, if the app verifies it came from the approved source and have not been tempered with, then it is much easier to lean on ASLR and other OS level security to make it harder to extract the authentication info.
Multiplayer game operators have obligation to curb modified clients so their actual paying clients have a levelled playing field. By ensuring their apps are only distributed via approved channels and unmodified by malicious players, this improves their odds at warding off cheaters creating a bad time for those that actually pay them to play fairly.
These are just simple cases where this kind of security is beneficial. I am glad Android is finally catching up in this regard.
Upload it to the cloud and make it someone else’s problem to deal with keeping up with the physical medium changes. Then your descendants only have to worry about figuring out how to deal with an outdated file format they can no longer open… and even when they can finally open it, it’d be super low quality… just like how we have to squint really hard at videos from VCDs now days.