Can you just pull the plug off?
Well, you never ever do that, if you do then that might cause big problem. To turn it off there is way of shutting down, use it to turn it off safely.
Advantages of turning it off every day
- Less usage of electricity: Usually desktop/PC consumes quite a bit of electricity, so by turning it off you will be saving some electricity that means you have pay less electric bill.
- Solving Temporary problems of the system: By working continually the system might developed some temporary problems. So if turn it off and then turn it back on again it can solve those problems. Well, this case I think "Restart" option is better.
- Protection from slowness: If you use it for long time it might get slower, but if you give it a break by turning it off it will regain the normal speed again.
- Relief from the fan and notification sound: Well, I haven't use noisy PC for long time but in the shop (where I work) the till makes so much noise and I hate that, some times I feel like breaking it down. But then again think that if I do so I'll lose my job. So by turning it off it won't drive you crazy.
- Durability: Well, of course if you use less of something it makes the thing last longer.
Disadvantages of turning it off
- Start up time: You might feel uncomfortable to turn it on and off all the time, and it might even take some time each time you turn it on. Plus if you turn it off without saving the file (which you were working on) you might lose it for ever, unless you have got back up for that file.
- Electricity usage: It is true that when you keep your PC on it keeps consuming the electricity, but if you are doing some projects and sometimes you just want to turn it off for few minutes then it's better to put in "Sleep" or "Hibernation" mode. If you do that it won't effect your work and it will consume minimum amount of power.
If you think that you're not going to use it for long time then it's better to shut it down. But if you think you will use it in few minutes then it's better to keep it in "Sleep" mode.