If God intended us to use mouse instead of keyboard, our hands will be terminated by USB inteface instead of fingers... ;)
Decent GUI design is not straightforward. Why?
Because we have different expectations from audience.
Pictures (icons) versus text
There are two kinds of memory :
(1) researching memory (when you are learning something first time), and
(2) recalling memory (when you know it, but need little reminder, little association).
Researching memory works better using words, text. Recalling one works better with graphics.
Micro$oft spent millions researching this issue, so they have icons (to remind), but also ToolTips (yellow text bubble), when mouse hoovers above button and you are obviously not sure what button does.
Keyboard versus mouse
Mouse is better in 'research phase', when you do not know exactly what you want and how to accomplish this, or to point on something. Later, when you know ways and shortcuts, many people prefer to switch to keyboard, because there are mu more possible combinations 'on the surface', so we do not need to select in multiple levels of menu. Yet many never do keyboard shortcuts, will be stuck to grab mouse i.e. when they want to move focus from one field to another, and will never try TAB. Many of you probably know the itching when somebody is switching between mouse and keyboard all the time, even for task easily made by keyboard only? Seconds fly by... Maybe I am not patient enough... : )
Many also know frustration when i.e. in Nescape navigator you cannot go BACK to previous page using backspace as in IE, and you need to grab mouse...
There is rule of thumb that if user user same program more than 10-15 hours a week, it is worth to learn shortcuts. If uses less than that, s/he will probably forget them.
I remember my embarrasment when I returned to programming after couple of months pause, when I struggled to do on conscious level many things what I did before without mind effort, you know you think about it, and fingers just do it.
Same story with driving a car - You are good driver when you switch turn signal on and off without thinking about it.
Also, some people are harder to understand even simple concepts.
I have colleague of mine, using Win/PC not too often, and it took me about 10 years to teach her that Ctrl+C will copy 'something', and Ctrl+V will paste it. In these 10 years, I explained it about once a month for different programs, until it sinked in... : )
From other point of view, I know about a case when accountant rejected one system and preferred another (ours :), and one of the reasons was that our system was capable to entering data solely by keyboard, but competition relied on mouse too often, slowig down plain data entering. We were lucky they noticed it. Usually this kind of feedback you get only after some time using system.
Summary:
IMHO, many profesional users prefer keyboard, if feasible (not for pointing into graphics, of course). Many of them like possibility to build and adjust shortcuts.
I know I do. My favorite editor MutiEdit is so customizable you may find new features after years of heavy usage.
BTW, how many of you know that you can open combo-box (pull-down list, HTML SELECT via Alt-DownArrow, or even F4? Try it i.e. in MS Word - font pull-down.
(Sorry if two kinds of memory above are called and translated differently in english - I read about this concept not in English. If somebody knows established translation, please let me know, I'll be glad to update.)
pmas
To make errors is human. But to make million errors per second, you need a computer.