It's more about the days where you have a busy day and only have time to do a quick in-and-out of your house.
I don't know about you but often times I will have days where I am super busy at work and at the same time things are happening in my personal life (weddings, births, funerals, buying a house, selling a house, flight layovers, hobbies etc...) and I simply don't have the time to stop sometimes, those particular days can have you going over a day not being able to allow the device to fully charge. Days like that you will want to plug in for maybe 10-30mins depending on how much time you have and you want enough charger to get through.
I wish the world was as perfect as simply plugging in for a whole 3hours every single day for the rest of your life, but it doesn't, life happens. You get to bed and boom, a phone call, your parent is in hospital due to health/old age or a friend needs help, or your kid is in trouble or even worse, you are having a health issue. Days like that, you quickly realise how great it is to have fast charging. The Huaweis charge so fast that within 10mins you are good to go.
Another great thing with fast charging is that many Power Banks now support it, so even if you are mobile with a Power Bank, your phone can get a decent charge within a very short time and not have to deal with keeping it plugged in.
In a perfect world charging your smartphone for +3hours would be fine though.