There's a small benefit to adding the n after the cd: When my thought process goes like "I need to go into directory" I can already type cd, then "oh that doesn't exist yet" then I can type the "n", then I can type out the "foo". You could possibly argue though that "cd foo -n" would be the right thing to type then. Or, finish "cd foo" then ctl-a "n" as you say.
