A reasonable point but think instant KK is more important on AC because of AC's "worst in class" reward seat availability. If you are with AA, DL, NW, CO etc you know that you have guarenteed access to reward seats (albeit at 175-200%) for all seats even as a basic member.

This isn't the case with AC. Drop below SE and you may not be able to get the reward seats you want. Elites only have access to the back cabin through instant KK, and Prestige and Basic don't have access at all. This just isn't the case with the other N American airlines where all members can get the seats they want.

I'm sure that there are some SEs who don't care about instant KK. However, given ACs lousy reward seat availability I think it is more important with this airline than with others.