Old Skool planning for the life-cycle of software used to be that:
1. On release it runs on high-spec hardware
2. Within less than a year most mid-range hardware will run it.
3. By end of life-cycle it will run on virtually everything out there.
If they designed for the machines that were around at the time then they might have to leave out some of the gee-whiz stuff that everyone loves so much ;)
The hardware people are happy because it drives sales, the software people are happy because they don't have to bother too much about efficiency.
This is all very well as long as the hardware is rapidly getting better but this is no longer really the case. The lastest machines are not light years ahead of kit which is a couple of years old.
The jump from desktops to laptops has probably lead to a decrease in average graphics capabilities.
Also for the first time there are low spec machines which are starting to give a half-decent user experience and the latest version of Windows won't run on them.
It takes a while for a lumbering giant to change direction. I'm guessing that they're working on something, perhaps even a cut-down version for the next release. When that arrives I might even prefer to run on it on my more powerful hardware.
Apologies for the slight tangent.