I would expect it to also be less expensive but they don't show us that information.
I personally wouldn't mind if my fuel mileage goes down if the cost is also proportionally lower.
Also, ethanol has a energy density of roughly 2/3 that of gasoline, so yes e85 would have 5% less energy than gasoline with no ethanol, not e10, which is what I see as the listed price in most places. When doing a price comparison, it should be against e0, not e10 if you are expecting a 5% energy difference.