A lot of these are integrations that either supply other entity domains (like the air quality sensor) so are already covered by the template sensors/ numbers/ switches etc… Or have specific user defined entities like Generic Thermostat that are easier to define than templates.
What about the media_player, device_tracker, and remote?
Take the media player, for example:
A template would allow the on/off to turn on a series of devices, the volume to control a sound system, and the media controls to control a smart tv.