Vacuums, for instance, are much better now since manufacturers were forced to adapt and innovate.
The problem with stuff like kettles though, is if you half the power available, then to do the same job you have to use the other thing that can't be restricted - time.
If it takes a kWh to do a job then it will, give or take, proportionally more time to do it with less Watts. You save nothing.
If we had stuck with the old fashioned hoovers but with weaker motors, it would take much longer to clean up and the no power would be saved. Luckily these devices were forced to improve and this is how it's supposed to work.
Of course screen refresh cannot go by this measure, so gaming PCs are a different story.