I totally agree, that it's better to include it from bootstrap only, but that's just not my call to make such a change.
I must point out, that I made my phpunit.xml file from dbproperties.xml.dev according to the instructions provided in its comment, and it doesn't mention any bootstrap. Without this line I wasn't able to run tests for this particular class only, and if you'll look at almost any other functional test class, you'll notice that most of them explicitly require_once this file.