Nikon and Panasonic do void the warranty, however. Canon voids only the software/firmware section but the remainder of the camera remains under warranty.
A commenter suggests that Canon’s decade of experience with the CHDK and Magic Lantern community leads them to understand the importance of, and the value added, by external software.
Canon has, so far, been the only camera company that understands the value that software applications bring to their brand by creating an ecosystem that expands the market for Canon cameras. I have spoken with other camera companies directly – and this year some of the others are finally starting to see that there is value in adding applications to cameras but do not yet have products to share.
Prior to this year, an engineer with one of the big companies said they would never allow 3rd party software to run on their products as it had the potential to harm the customer experience. To which I replied, “That must be why Apple prohibits software applications being added to the iPhone and iPad” … not.