Its a setting and its on purpose ! "Hide Extension if known File Types". Its Â one of the first things I turn off in Windows folder options every time after installing an O/S (I've done alot at my job over the years) whether its XP, 2000, 2003, Win7, 2012 etc..
This was a case of Windows trying to be more Mac-like in the GUI andÂ it has been like this forever.
Dude's right it increases risk but seriously he's expects them to revert to DOS style file display convention NOW ?Â