Your question, to me, goes beyond the OP's original question. What is the purpose of a mouse? I started working with PCs in 1984, when DOS was the one of the primary operating systems. My first job was writing dBase code. I used Word (DOS version) as my code editor because it supported split Windows (in PCDOS) and allowed me to do cut and paste between the Word windows it also supported using a mouse. I could use the mouse to select text to copy and paste between the Word windows. (Remember, this was before "Windows" as a user interface/operating system was available. In a PC/Windows environment the mouse is essential. However, there are many times when I use keyboard combinations to speed up selections or actions when moving my hand to a mouse would slow things down.
The iOS environment changes everything. It is designed for touch. The first iPhone was introduced in 2007 and everything in the iOS operating system is focused on touch. It doesn't appear to support a mouse, since most iOS users won't have mouse with them (think iPhone) when they are using the device.
I use a mouse well (both right handed and left handed) when necessary on a PC. I do not see the need when I am using my iPad.
Great question. "What is the purpose of a mouse?". This is also very pertinent : "I started working with PCs in 1984, when DOS was the one of the primary operating systems." I've also used computers professionally when it was just a terminal.
In a nutshell, the mouse let us point at things accurately. This allowed for windowing, which allowed same screen multi tasking. It also allowed for quick navigation to different window elements - this can include the content which could be text, or (thanks to the mouse) graphical content, or quickly jump to a spreadsheet cell, rotate a 3D model etc.
So the mouse let us do old things faster - jump accurately in text documents, and accurately and quickly select text, spreadsheet cells, etc. It also let us do new things - graphics, 3D models, quick window selection. You can also just ignore the mouse when it slows you down.
For argument sake, lets call the majority of those tasks actual WORK. I'm not belittling anyone, just for argument sake lets define those as work. Folks get hired to write, design, 3D model, do spreadsheets, etc. All of these require accurate pointing.
You say "The iOS environment changes everything. It is designed for touch." Yup. And look at the software that was included with the original iPhone. They are all personal, communication, or utility apps. Generally, and please excuse this generalization, people don't get paid professionally to email, browse, check the weather, use maps, call someone. All essential PERSONAL tools, but not WORK.
So I'd like to draw a line in the sand. I'd like to put forth that WORK related tasks require accuracy. And in a nutshell, my fat fingers aren't given them to me. Which is completely fine for personal tasks, but not, from what I've seen, most traditional work tasks.
Was the mouse better than the terminal at work tasks ? Could it be used in conjunction with pure terminal text type interactions and make them faster ? Yup. Could it make other traditional tasks like spreadsheets and writing better ? Yup. Did it usher in a new type of work ? Yup.
Is Touch a step forward in these WORK tasks ? Not from what I've seen. Will it bring forward a revolution in design using Touch ? Unlikely. Will it bring the revolution with the Pencil ? Yup maybe - but then thats not Touch. Maybe for the Creative Arts the iPad with Pencil will usher in a revolution just like the Mac did. That would be awesome. But the Mac managed to do that AND also make old tasks better - it didn't get in the way of old tasks.
Also, if this is the case with a revolution work focused on graphic arts, why did Apple go out of its way to introduce a keyboard case for it but then ignore the revolution of accurately selecting things ? If Apple's iPad keyboard was a flat surface that acted as a huge trackpad, then it would of been like the Mac. It makes old things better, and it introduces new ways to work. Now that would of been a current day revolution.