Just using windows/mac because lots of people do is also a poor reason. Computers are tools, powerful and flexible but only tools. It the flexibility to use a single device for work and play. To control your house or support thousands of other computer systems running applications for millions.
I have extensive experience with windows running in home and international enterprises. There are plenty of things lacking in windows, so true in linux and Mac. That's not a good question. What would a Linux desktop offer over a windows desktop? Simple - security. Secondly lower price point for performance. So if you are prioritizing security and/or you want a system that will perform the same as new hardware with older less expensive hardware or possibly you need more performance (Developer or Engineer) than you can get from windows Linux is a logical choice. Often because the IT support only knows windows (and how to remove Malware for a cost) its the training cost that has companies reluctant to change. Portables and tablets are changing that. Since tablets out sell computers, an Android client (largest market share in portables currently anyway) is what you are really advocating for yes?