While it's surely a nice feature to customize the window/document title for the report, I would like to raise the following questions about the proposed solution.
Isn't this a more general feature? At first look, I would rather say that customizable titles would be of interest not only for the Surefire report but other reports as well. E.g. I could just go ahead and open a related issue for the Changes plugin because I would like to have its report named "Release History" instead of "Changes Report". But if each plugin implements this feature on its own, things get error-prone, hard to maintain and might be inconsistent. Therefore it seems this feature is best realized at some general/shared place like the Site plugin or Doxia.
What about internationalization? One can tell the Site plugin to output reports for various locales but the proposed patch limits the user to only one title string (i.e. only one locale). This does not fit together. If the user wants to properly change the title strings, he would need to specify something like a map locale > string.
I could imagine something like this in the POM:
<en>My English Title for the Report</en>
<de>Mein Deutscher Titel für den Bericht</de>
Letting the user provide customized resource bundles as some kind of overlay for the plugin's internal bundle might be another approach but this seems kind of overdressed to me.