Understandable, but what's being lost in the optimization process, is both adjustable, and in the default settings virtually imperceivable. But I'm guessing there is a great deal of cruft in the PDF format. Part of which is the boiler plate header trash that froths on about how cool Adobe is, and the rest is duplicitous formatting and object description code.
The example that sold me on the program was a 35Mb (in house created) sales brochure that one of the staff was trying to stuff through our mail server. I ran it through NX and it gave me a 3Mb file that looked (and printed) identically to the bloated original.
-Stoic Joker
I'd guess that they main problem with your sales brochure was large jpeg image files embedded within it and that most of the size gain came from reducing the resolution of those.
PDF editors like Adobe Acrobat and PDFXchange Editor provide optimization tools that give you full control over the size and compatibility of a PDF file. How you handle the many different options depends on what you want to do with the PDF.
-xtabber
Many people don't do that, however, and you can be stuck with the results if you don't have an editor, and the time to check the settings. Having something do that for you is well worth it. I had someone accidentally distribute a book unoptimized. A bit later, they redistributed the optimized version, but this would have made me not have to even deal with opening a 256MB PDF in the meantime.