>Because google actually cares about hardware and software security.

That statement might not have aged so well, especially consindering googles attempt to lock out apps from their devices, If the developers do not comply with being oficially registered.

There is a difference between security and privacy or freedom of use. Locking down the device to only allow a subset of apps that Google has some control over (by requiring developers to register) is a measure that can increase security, even though it obviously takes some control away from the end-user.

The fact that the play store is not exactly known for exceptionally high standards w.r.t. malware, or that there are lots of valid concerns that come along with a company controlling who is allowed to supply apps for the device is a different topic.

Don't mix security and freedom. They're commonly opposed to each other.