I started the topic linked below to discuss this subject a while ago. There are definitely differing opinions. Most differing opinions seem to point to a users workflow and purpose for using Cubase. But, no one has yet given me any really good reason for recording a mono audio source, connected to a correctly assigned mono bus to a mono audio track… for anything.
Because of this, I would venture to state that if Cubase didn’t even offer it’s current mono audio track option no one would miss it.
I would love to hear if my last statement is totally full of beans as my original purpose was to learn something about the mono audio track use. I don’t know if my topic in the Steinberg Lounge linked below is the place to discuss… or here. I suppose the mods will decide. 
Regards 