Since there is only T6, T7, T8 we should rename the tiers.

T6 Change to Equus.  Because it is born and caught in the wild.

T7 Change to Thoroughbred.  Because you have to breed to get them.

T8 Change to Champion.  Champions are bred from the best of the best.

Obviously Dream and Mystical would be kept the same.  

You could name the tiers whatever you want, but Tier 6, 7, and 8 is kinda meh.

Or maybe they should just remove the tiers altogether at this point. The tier system is obsolete now between the dream horses and mythicals and the removal of the lower tiers. Have all of the horses be one tier and unlock all of the appearance options (t1-t8) for all of the regular horses. Have all of the combinations available through breeding. Keep the courser system the same as that would still keep breeding and training relevant.

And if they actually gave a darn for the players, all appearances would be available to the horses as they were before and not hidden behind some paywall.

I'm completely agree. That was a dirty move on their part.