The accordion is more common in popular music than its reputation might suggest. For those who are curious, Google "Those Darn Accordions" - a California-based band that has done some wonderful things with classics such as Low Rider and Stairway To Heaven. Really!
Why not accordion ?
To my point of view it's one of the most universal solo instruments, but not widely accepted in any classical or jazz orchestras or bands. It's also sophisticated. I'd say extremely sophisticated. In order to deliver smooth and artistic sound it may require long and extensive practice to handle bellows and position your hands properly. In addition there are two button boards that can deliver sophisticated polyphonic parts that can create an impression of small band inside one instrument. You can also count on fingers great accordionists while you can have an endless list of great guitarists or saxophonists.