Android 5.0 unencrypted despite being promised

How come???Yes,it is.During its pre-launch,it was promised that Android 5.0 would have a encryption feature that would be enabled by default.But this promise seems to be just a promise.

Encryption=Safety

In its blog,Google explained that "user data partition would be created at the first boot with encryption being done at default" from the moment the device is installed with lollipop.Nexus devices certainly have this feature enabled by default.But,the rest of the devices that runs on Android 5.0 have the absence of this feature.
It has been assumed that encryption would slow down the devices(which could be the reason for the manufacturers not having this feature). Not using this feature just to fire up the device is a bit sluggish and disappointment for the users.