Late answer (seven years after the initial question), but I think it can be useful.

The rationale for changing the name from convert to magick was, I think, that Microsoft Windows already provides a "convert" command. The Windows convert command is used for converting a file system type (e.g. FAT) into another (e.g. NTFS).

Of course, one wants to avoid the confusion. Before that, one was probably reduced to specify the full path of the imagemagick command on Windows systems, or to run the command in a console prompt with a special path for imagemagick.