So, my company issued development machine is a beefy desktop full of xeons and graphics cards (necessary for the specific work I do). It's fantastic for 95% of my work life but sometimes I want a computer in a meeting with me to take some detailed notes, have a document/code on hand, or give a presentation.
Obviously, there are ways around all of those situations. I can email my slides to the presentation machines in the conference rooms, etc. But they don't really beat the convenience of just grabbing the computer I used to make the ppt and knowing that everything will work. Sometimes I get quite jealous of colleagues with laptops.
And then, of course, there are the aforementioned cases of travel or wanting to work from home instead of coming in.