The problem with a lot of industrial design is that it's cynically conducted to sell the device in the first place, rather than to actually be any good in the long run. That is to say, the device is designed to appeal to the shop-floor browser who's making a snap judgement between competing products, rather than to actually be a brilliant product for them to use year after year. Once they've bought it the game is over as far as the manufacturer is concerned, as long as it doesn't actually break down, because poor usability does not invoke the warranty! I came across a great example of this recently in the control panel of a Siemens fridge. Behold:
There is one button on here that you will use several times a day. The rest you may use either never or once every year or two. Care to hazard a guess which one is the magic button of actual usefulness? It's the one marked "dispenser". Or to be precise it's the one marked "dis-penser" split over two lines, such is their lack of grace. This button switches the ice/water dispenser between water, ice and crushed ice. To get a glass of iced water, you have to press it a few times to cycle round the options as you fill your glass with ice, then water.
This should be the only button on the front of the fridge immediately above the dispenser, and it should be very clearly labelled. In fact arguably there should be three buttons, for water, ice and crushed ice, with LEDs to show which one is selected. They should be labelled "Cold water", "Ice" and "Crushed Ice". Imagine a visitor to your house approaching your Siemens fridge for a cool drink. They will probably accidentally defrost your freezer then child-lock the fridge before giving up and having tap water. Maybe it's an eco feature?
The controls that are not related to the water/ice dispenser should be far away from it, possibly inside the fridge door or behind a panel, so as not to pointlessly engender confusion and accidental fridge reconfiguration when trying to get a refreshing beverage.
So why have Siemens chosen to take this insane path? I don't believe they could be so obviously dumb, so I assume it's a cynical ploy to sell more fridges. Imagine Joe Shopper, strolling through the aisles of Currys, looking at endless gleaming monoliths of cool technology. Joe wants a high-end fridge, the sort of fridge that says "Joe is a classy guy who won't let anything stand between him and a glass of brain-freezingly cold water." Given two stainless steel slabs of Germanic engineering with largely identical specs he's going to go for the one with the most 'impressive' control panel. So actually Joe, it's your fault, but the nice guys in the Siemens design department must cry themselves to sleep at night.
I object to the first sentence. Whilst some designers are unthinking time servers and careless about the modus operendi of controls most aren’t. Thus you can probably trace the cause of this entirely witless example to other causes. Design commonly has to pass through the usual suspect filters of cost, production, commercial inputs, having common parts with other products in the range,the bosses secretary (not kidding very true), parts (inc control panels) sourced from the far east etc. None of these are an excuse for this particular design failure as it would be easy enough to find a much better example ranged alongside in various sales emporiums. It does have something in common with another paragon of Germanic design; much of the VW/Audi range have rows of similarly neat looking buttons which are not always suitable to their function, or as your main point, their relative importance. Are they criticised much? E-type jag was as bad.
Long long ago I recall on taking up a new job that whenever I wrote a document I had to have the vision of a gentleman called Councillor Brain in my mind. He was a great bloke with many real personal qualities. Alas, Brain was entirely the wrong surname for him. His difficulty in that area unluckily was shared by a number of his colleagues. Critically they had to be able to understand what I was on about and what was involved, otherwise I would would be either on a road to nowhere or they would make entirely the wrong decision just to prove a point. I do wish designers of very many modern consumer products would have someone in mind who was none techie or had poor sight or who were getting old.