Most of the travelling public is better off right now, although Tango is screwing some people who want to make connections or stopovers because the mainline frequency has been reduced on some routes. I think this will sort itself out shortly as AC moves most of their domestic flights to the "discount market". (I predict this will happen sooner rather than later.) Status miles are still an issue ... the frequent domestic traveller is not going to like being busted down to Aeroplan Basic because they are flying on Tango. But then does it really matter with the gutted Aeroplan program? Aeroplan isn't really a loyalty program anymore.

I'd argue Tango is bad for AC, because the revenue they are losing from the former high-yield customers is bound to exceed the small savings they get from adding additional Y seats, not serving meals, and not interlining baggage.