Microsoft Word used to "auto-correct" the ASCII codes 0x22 and 0x27 to those.
Also, ISO 8859-1 was the default character set for the web, and MS Word was in common use for making simple web pages... but without narrowing from CP-1252 to ISO 8859-1.
This had the effect that when you browsed one of those pages in a browser on another operating system, the quotation marks rendered as empty boxes ( = illegal character).
This really messed me up when I started programming since those quotes will not work when writing in a language that expects a set of the same character but they may use the same glyph. This is one of the many reasons I have my systems set to English.
I agree that for a normal writing environment it may be advantageous to have it auto replace since it is also just easier to hit the same key twice and have it auto open/close.