zpool command should have better support for feature flags
Currently the only way to enable feature flags is using the 'zpool set' command to set a 'feature@...' property to 'enabled'. And the only way to see which features are enabled is to check the 'feature@...' properties with 'zpool get' or 'zpool list'.
For better management of feature flags:
The 'zpool upgrade' command should enable all features on a pool and provide verbose output about what features it is enabling.
The 'zpool status' and 'zpool import' commands should provide information about pools which do not have all available features enabled on them the same way they do about pools that are not upgraded to the highest available version number.