I‘m right with you as the flat screen is basically the only thing I miss from the time I had an Ultra, but alas from Apple‘s perspective I don‘t think it would make a lot of sense. As a third model in an Ultra – Ultra mini – Series line-up, it would use up valuable engineering and design resources to cater to a probably rather small market segment (i.e. people who would buy Ultra mini but won‘t buy an Ultra regular or Series instead). As a re-design of the Series Watches it may hurt more than help sales as you would now have no option in your line-up anymore for people who like the current smooth, pebble-like design (with curved screen) better.