Why there is no option to turn off mobile data in Spotity?

I have a Datalimit on my iPhone. When I am on the road, I try to use only offline/synced playlists. I put Spotify in th Offline mode, to make sure no tracks are streamed accidentally that are not synced, because they are new etc. 

However, offline mode also prevents syncing playlists over WiFi. So all my subscribed playlists are NOT updated anymore. 

So I have to switch from offline to online mode all the time, depending on if I'm on Wifi or on Mobile Data. 

Mistakes easily made...

Turning Mobile data off in the iOS settings is no option of cause, because you will lose also email etc. 

An option to turn off/on Mobile Data will solve this and will make the life so much easier for people with a datalimit. 

The current "offline" option is useless anyway, because it makes no sence to limit syncing and streaming when you are on WiFi. Only for Mobile Data.