True, but I like what Canon has done here. The 16-35 f/4 IS is "affordable" and great for most photographers. The 16-35 f/2.8 II is still in production for just a bit more, and now the 11-24 f/4 is available...or will be. The price, size/bulb, and extreme UWA is obviously aimed at a very dedicated niche. That group will likely not have an issue investing in the Wonderpana system.
While many do not use f/2.8 much for UWA, updating an f/2.8 UWA lens would complete the trifecta.