I've had appliances go faulty at my house and having a handy accessible isolator has been massively helpful.
Agreed, In my view its poor practice to not be able to turn the appliance off without pulling it out from the wall.
Even from a a functional switching point of view, a lot of appliances only have 'soft' on/off controls these days and having a proper on/off control is useful.. E.g. setting the washer going and needing to get back in when the door has locked... most will let you back in, but only after having the power off for 5 mins. I wouldn't want to have to pull the washer out, or turn the sockets off because I'd forgotten to add the soap capsule before pressing go!