Hi,
Itamar:
With all due repect I don't think this is the proper / default behaviour of 'Save As'. Having just checked with Microsoft applications eg Word, and Adobe eg Photoshop in both programmes 'Save As' puts a file extension after the file name. Also with smaller software companies eg Top Style CSS editor, again extension is placed after name. I can't find any software on my computer where this isn't the case.
Daniel:
I agree with you from a usability standpoint that this function should behave like most other software students use on a daily basis.
Generally when people suggest 'fix the user' it is an indicator of software that isn't designed in a user-friendly way.
~thomas