Don't worry I don't use "Enter opening something" as my only criteria to judge the discoverability and the ease of use of an interface -- and like you said Windows is full of arbitrary and/or curious keyboard choices -- but pretty much like all interfaces. (However, I still find enter => renaming really weird :p )

As for Cmd+Q and Cmd+W, those might be somewhat more intuitive, but only for some languages, and arguably only very vaguely intuitive for Cmd+W even for english speaking people.

But then again, I don't think there is a real notable difference in the end between most modern systems. It's more of a question of what we are used to.