Consider the following use case. I downloaded tracks for many hikes I want to do, but they are in different national parks (each with its own map). When I go to any one park, I would like to see only the hikes for that park. I can "select all tracks" and then go to the park map: this will show all hikes on that map, but it seems to slow down Locus a lot. I can attach the park name to the beginning of each track's name so that they all are listed together in the track list, but the track names tend to get clipped. If I could add my own track types, I could have one type/category for each park, and filter by this.
At present, I have just mentally assigned existing track-type names to certain parks ("Exported" is "Yosemite", and so on). It works, but it could be nicer.