This file may be distributed and/or modified under the terms of the GNU General Public License version 2 as published by the Free Software Foundation and appearing in the file gpl-2.0.txt included in the packaging of this file.
Actually, the clause is recommended by the FSF. Projects that remove the clause do that fully intentionally.
Considering how long copyright lasts (70 after the death of the author), it is IMHO pretty short sighted to make the licence of a project stuck in time and unable to react to any future legal challenges.
It just means that the owners of the project copyright are the ones who decide how the licensing of the project will change over time. This is not short sighted. It is the best way to ensure that they can keep their code free. If you adopt the "or later" option, you are letting your code be forked under the terms of whatever license the FSF decides to attach the name "GPL" to. The FSF has already shown that they are willing to back away from free software by adopting the non-free AGPL (it does not satisfy freedom 0). Why believe that they won't compromise future versions of regular GPL, too?
By omitting the "or later" option, the project owners can take a look at each future version of GPL, and decide if it is still free and meeting their concerns and requirements, and then update their license if appropriate.
The project still has control of the license it offers the project under; of course, if it depends on software from anyone else that is on limited-to-GPLv2 terms (which lots of projects are), it can't change to any other license (whether GPLv3 or non-GPL) without either replacing the outside software or getting the copyright owner to agree to different licensing terms.
The project at issue here appears to use GPLv2-only because they are dependent on other software that is GPLv2-only.