Trust me when I say I am incredibly sympathetic to your complaints. Replacing the AI art is at the very top of my list of goals. I think it served its purpose as a fast and dirty way of making enough of the core game to see if people would be interested in more. The main goal of the next update is to drastically improve consistency and rework many of the original scenes. The current lack of consistency is one of my biggest gripes as the developer, but I hope you'll check in either next update or in a year or two when I've had time to refine the game!
If it seemed unintuitive to gain access to Tier 2 content, I can certainly have a look at making it more straightforward for the future. Sorry for the confusion!