Hi,
The point of Feature color is to help visual management when dealing with stories. This allows the human mind to take a shortcut and categorize stories automatically, which is really handy when dealing with dozens of stories which are displayed in the same backlog.
Tasks would not benefit that much from in turn inheriting this color. Indeed, unlike stories that don’t show their feature explicitly, tasks are grouped by story in the task board and the story name is displayed. The feature color is also already visible (left border of the row). Finally, unlike features and stories which are both business items, tasks are technical items so it can be useful to leverage visual management to classify them according to technical criterias rather than business ones. For example, for the development of a client/server application you can pick green for tasks dealing with frontend development and blue for the backend.
