Why do you need a mouse on a UMPC?

Something I discovered after getting over all the specs was the all important button set on the face or the side of the UMPCs. I realized quickly that a major difference was in the number of shortcuts and the presence of a mouse stick and mouse buttons. I started asking myself, why do I really need a mouse button on a touch screen device? Isnt the whole point to use my finger as the mouse?

I read that many people say that the lack of the mouse stick on the Samsung Q1 was a dealbreaker for them. I was immediately thinking, either they have very dirty fingers or they are just too big. For UMPCs I generally see two categories of usage scenarios, one where I interface with big buttons where my fingers will be good enough. And the other where I have to do more detailed work on the device. For the detailed work in the field I saw that I would most probably use a combination of the pen and/or my finger or fingernails. When in the comfortable chair in my office at work or home I would most probably have access to a mouse and keyboard as well. Even with only a keyboard I can see myself picking up the pen and click something as a faster way to do stuff than to grab the device with both hands to navigate the pointer with one hand and click with my other hand. I just never was comfortable with these on laptops either so maybe thats why I feel so sceptic about the mouse pointer.

So what does e.g. the Samsung Q1 offer instead? It has a brilliant set of shortcut buttons instead. Something I can see myself using more often than a mouse. Like jkOnTheRun I would probably configure one to toggle the IE browser fullscreen and other nice things depending on which application I am using. For a UMPC I see that the major set of applications that I am likely to run on it will be very simple interfaces with big buttons or otherwise shortcut enabled though the buttons on the device.