If a user were to setup a screen made of multiple switches it is impossible to tell what graph is specifically for. A graph title of "switch7:if10" tells little about what the switch is for. There was a patch for 1.4 which allowed for custom graph titles in screen. Another common work around for this problem was to have a screen cell reference a web page which contained text which which described the cell either above or below. The challenge to referencing a web page was maintenance.
If it were possible to have a free form text field in the screen the above use cases would be better handled, and would be much easier to manage.