The GPL, unlike the MIT license, protects against people adding a small thing to an open-source program that might become necessary to use it - thus taking it out of being usable in its open-source form. So the GPL is a good thing.
However, to sue someone for violating the GPL, one has to have "standing"; that is, some basis on which to claim that one is the injured party. While potential users of software covered by the GPL could indeed have standing, a much stronger basis for legal action would be if one was either the authority responsible for the GPL - Richard Stallman and his organization - or the author of the GPL software in question.
A random law firm, even if acting in the public interest, but not actually representing someone specific who is affected directly by a GPL violation... would seem to lack standing. So this issue suggests itself based on the events described in this news item.