It's not about whether other cities 'deserve' a show, it's about trying to grow your market.
Sure, holding all the big shows in Vegas is easy and comfortable and probably more profitable in the near term, but it's also short sighted.
To grow revenue you need to grow the fan base and one way to do that is to have shows in new places and reach new people.
I think that's the intention with the Fight Night cards They're like UFC regional shows that they can hold in lower profile locations, while they save the big shows for major locations.
10-15 PPV's in major markets, and the Fight Night cards can be spread around. Like they just held fight night in Nashville... a decent city, but clearly not a sprawling metropolis.
Unfortunately they have a lot more cities than shows to go around so the smaller cities in less lucrative market like Calgary are going to be lower on the hit list.