The 'best' user interfaces (UIs) are invisible.
Catchy statement, right? After all, UIs like those are the ones you don't notice, cause you're busy getting stuff done.The most effective UIs are the ones that make it easy, and even pleasurable for you to do what THEY want you to do.
And what a UI wants you to do may not be what you want to do. (I'll leave the question of 'best for whom' aside for now.)
For example...
Ahh, hello human, I want you to stay with me, and spend money continuously, for as long as possible, so that my owners can profit from you. :D
Human
I want to win! Winning makes me feel great! I'm sure my next big win is just around the corner!
This is rather different from you, the human, saying, I want to stay in this place and spend money continuously, for as long as possible.
Hi there human, I want you to desire everything I have on offer, and spend as much money as possible, so I'm gonna make buying as easy as possible. As far as I'm concerned, you can't buy too much! :D
Human
I wanna look good to other humans! And I don't wanna be ripped off while I... ooh shiny! I need this! And this! And this! Ooh and this!
Clinical UI (E.g. Doctor)
Hey doc, I want you to accurately record all the relevant information about your patients, so that your patients can get the best care you're able to provide. :D
Human
I want to make sure that I get everything down accurately, so that my colleagues and I are able to help our patients achieve the best outcomes possible.
Usability is ethically neutral - UI design isn't
There's an assumption that UIs that are user-friendly, and 'delightful' have our best interests at heart. From the examples above, this obviously isn't always true. It may not even often be true.
Casino UI is a great example of conflict between what we want, and what the UI wants us to do. We appear to be travelling on the same 'journey', but at the end of the day, the relationship is parasitical at best, and adversarial at worst.
Online Shopping UI has a less toxic relationship with us, as users. At least the UI isn't expressly designed to exploit our human weaknesses for profit. As a merchant's proxy, the UI very reasonably wants to make its goods attractive to us, and make it easy for us to buy stuff.
Clinical UI is what we tend to assume we're getting, even when that trust is unwarranted. It embodies the classic concept of 'best UI'. What Clinical UI wants us to do works hand in hand with what we want to achieve for our patients.
But even if the usability of all three UIs is the same, the ethical contrast between the three UI designs couldn't be more different.
When it comes to usability, it's important to remember that there's no moral value attached to how easy something is to use. Moral value comes into existence when ease-of-use and pleasure is harnessed to directing specific behaviours.
When we look at it that way, it's pretty easy to say: Casino UI is evil, Online Shopping is neutral, and Clinical UI is good.
UX and UI design are essentially the design of systems, products, and interfaces that encourage, reinforce, and reward specific user behaviours.
Whether the outcomes of these specific behaviours are beneficial or harmful to us - as users - is highly dependent on why the product was created in the first place.
So the next time someone tells you that all you do as a designer is 'make pretty buttons', tell them that the pretty buttons are just a small, unthreatening part of designing reward systems for sneaky mind control. ;)