What is your beef?
There is no advantage to the MAS version over the retail package on DVD. You get your updates through Software Update in the Apple menu. Folks with the MAS version get their updates through the MAS. When the next major version of iWorks is released, it will be a paid upgrade for everyone and it will only be available from the MAS at that point. Then everyone with the '09 versions will have to buy the new version through the MAS.
Truthfully, your version of iWorks '09 takes less disk space than the MAS versions of the individual apps. Your installation has shared libraries and other resources. The MAS versions are independent and have duplicate resourses using more disk space.
There is nothing to be gained by your belly aching about it. You have had it explained that this is the current situation and you need to accept it and move on to much more important issues in life. Such as, will your current Mac run the new version of Mac OS X 10.8 Mountain Lion when it comes out this summer? 😉