There was no assumption on their part, they changed the design of the screen to the ribbon some time ago now. You can still get to the pop-up in several ways (I noted two ways, one of which bypasses the Ribbon, you noted a very dramatic third way), and you can also access it by clicking on the angled arrow next to the panel label OPTIONS in the Hatch Ribbon gets you there too.
Now why the custom hatches do not appear for the OP would be interesting to find out when they post back that they are not in the pop-up either: most likely their location was not added to the Search Paths of the ACA program, or they forgot to move them over from their previous version. I can see all of my custom hatches in the Ribbon's PATTERN panel (you have to use the arrows) and in the pop-up under custom hatches.