The reason I put in the feature request.. No you wouldn't see it if just setting up via wizard, etc.. It comes into play when adding opt interfaces, etc. The mask is a drop down list - has to default to somewhere ;) Defaulting to the end of the list seems to be just the way it normally happens.
I do concur that the most common mask used as default might eliminate such new user mistakes.. But when it comes down too it, user has really nobody to blame but themselves - when setting up a static IP on an interface they for sure should be checking and understanding what mask they want to set on the IP…
Part of the problem is just users that don't really understand.. Just take a gander at how many posts you see where users have set the default mask on say 10/8 or 192.168/16 etc.. ;) And trying to make it kind of idiot/mistake proof while also allowing for more complex sort of setups, etc.