I agree and recall we had exactly this didcussion, after the launch of FSX and before we upgraded.
One input was to question what would be the reaction to the restriction of a sports car we'd bought to a manufacturer restriction to "not more than 30mph".
With all due respect, in that case, what exactly is the point in forking out good hard earned money on FSX at the present time, (not counting the cost of re-upgrading all the countless numbers of add-ons etc)
I have suddenly got very respectable frame rates for FSX on my old machine, and much faster loading times too. All very simple, just move all sliders to the left! Most of the scenery disappears, but the flight controls respond much more smoothly. It makes FSX flying more tolerable while I wait for Vista, DX10 and my new machine.