Fact, you will almost NEVER find a coulouir over 45 degrees no matter where you are as the snow won't stick.
Fact is many of the hidden extreme Sierra late summer Alpine couloirs such as Ice Nine
are not "snow" dependent for their ice. It is the melt water that collects and then freezes day in and day out over a period of a couple of months that creates their AI or WI value.
Also, cruxes (being a bulge or whatever) do count when rating a route, regardless of discipline. To say that a route with a move or two at .11a but is a consistent .8 should remain at .8 is totally illogical and unsafe for those moderate climbers thinking that they are just getting on a .8.
Another reason why variable extreme conditions are vital in determining an Alpine Ice routes rating in the Sierra. Giving it the highest rating possible when conditions are just right for it to be so/in, and including any possible extreme possibilities that may occur due to those conditions, allows for an accurate and safe rating for those to consider before getting on any Alpine Ice route.
BTW, that is the governing rating standard for all Mt. Blanc Alpine routes given by the originating Chamonix Guides. Gaston speaks of this in his Guide Book for the Mt. Blanc region. The Alpine Ice ratings throughout the Alps are also indicative of this. Perfect example of this scenario is the Classic below. It varies in degree of difficulty as the season progresses. In early spring after a heavy snowfall season, it is less difficult and the difficulty increases as snow melts out and the annual summer ice begins to govern, regardless of it's sustained "steepness". Also, in dryer winters, it is at it's height in it's assigned rating of difficulty. As mentioned by Alois above in his more eloquent post regarding this standard.
But you already knew that....