Many Computer Users around the world have learned to experiment their computers with various operating systems, Sometimes even an Operating System like Windows Vista can work better then Windows 7 on a particalar computer model.
Not All computers are the same that's why its important to have the option to try a different OS to see which OS performs best.
Next Time you purchase a brand New Computer make sure you ask the sales person if the computer supports Legasy OS, cause if it doesnt you might not even be able to try a newer operating system then the one it comes with either not just older once!
It will also help you find out if the sales person knows what you are talking about or are they just in for the money!
If UEFI(Unified Extensible Firmware Interface) boot becomes non-optinal this could force you to buy a new computer when a new OS comes out, todays computers are pretty fast and up to date since they are all 64bit based and as longs they are running on a SSD drive.
It's important to have a computer that will suport todays, pasts and future Operating Systems like it has always been upto now.