You are certainly entitled to your opinion. If you look at my diagram from way back, you'll see that people would like to be able to flick through fullscreen apps with gestures like everyone else can with one screen.
What they don't want to happen is the compensation of their other hardware (displays) because of it.
As it sits now, it functionally doesn't work well with multiple displays.
If you are looking for undestanding of why people might want to be able to use fullscreen apps and still have control of their other displays, simple read the history of this thread, it's all been said.
No one is forcing anyone to use FS apps.The real issue is that they never reallu updated Spaces (which I ignored successfully since there was no added function in having multiple spaces since they too moved all the applications when you switched to them.
With REAL control of multiple displays and fullscreen apps, the function, as it sits now, coupled with the idea that Mission Control works independently for each display (my idea) you could have virtually as many "Pads" as you do Displays, flicking through various ones and mixing and matching which ones you see on any given display.
I digress. You're opinion is noted but if you honestly want to know "why" someone would want this, then simply read this thread.
And for anyone who missed it the ten other times I posted it:
http://bugreport.apple.com
http://www.apple.com/feedback/macosx.html
These are both ways to directly contact Apple about issues. Of course this would probably be better suited to file as feedback. Apple does care about it's customers. It is better to file feedback then it is to post about it here.
If you are pressed for time, choose to send feedback instead of posting here, the former benefits you more then the latter.
-MIB