Since going full-time as an iOS developer, I have worked from home exclusively. Sometimes I am asked why I am not open to travel. Beyond personal reasons like wanting to be home to spend time with my family, the most important reason is that my home office is designed for maximum productivity.
My primary machine is a 2013 27” iMac with 32 GB of RAM. I use two external 27” LED Cinema Displays - one in portrait orientation - and I have a 15” Retina MacBook Pro open and running all of the time also. With this setup I can get a lot done very quickly. If I was to travel with just the MacBook Pro, it would significantly reduce my productivity.
Simply put, my clients get the best return on their investment in my time when I work at this desk.