Nowadays we all think about having as many cores as possible and not too long ago we all had single core machines. Until some crazy manufacturers got completely enticed by the idea of multiple cores, it was cool to have SSE1/2 and Hyperthreading, hell when MX and MMX came out shit hit the fan.
Now that you have a 4 core machine under your desk, in your pocket, in your bag, etc, would you use a single core machine again?
I could. I use a netbook with a single core atom almost every day.
I've used my i5 @ 5.0 on a single core it did just fine. Would I use an atom single core like you do? LOLILLLIIOLOLLOOLLLLLLOLOL no. God no. Please. No. God no.
Depends, i don't want my workstation to be a single core, but a laptop purely for writing some documents/watching movies I would rather have a better singlecore performance + longer batterylife.
I should also state that I know that televisions , appliances , automotive computers , network devices , ect.... still use single core cpu's. But those devices only need single core cpu's.
I was using a dell precision 670 workstation that I got used for a long time. Single core xeon with hypertreading and option for second processor. Was a beast and cheap but began to show its age.
The only single core computer I have in my house is my old Packard Bell which has an Intel Pentium 4 517 clocked at 2.93GHz with hyperthreading. This thing was a breast when it was new and even now it isn't too shabby on Linux but sadly it has outlived its usefulness especially since I have machines with multi-core processors that preform much better and are more power efficient.
Oh, and since I received my Raspberry Pi 2 I have been using my old RPi Model B which has a single core processor clocked at 700Mhz as a VPN on my network.