> Assuming your question arises from a state of ignorance, rather than from rhetorical flourish

It is quite clear to me that the parent's intention was to challenge the ritualistic "Why not MIT/BSD?" type of argument. It is the author's prerogative to decide which license the software should be under. While I use permissive licenses for my work usually, I see the merit in GPL licenses and might even switch back to it at some point. They serve different goals, and I suspect that in future we're more likely to converge towards GPL-like licenses.

GPL protects the rights of independent developers better than permissive licenses; and as software development becomes more accessible, we're likely to see more work pocketed off by companies without giving due credit, or even entirely forked off. GPL clearly recognizes that companies will not give back unless required by the law. If we're to have a fairer and more decentralized (political) power distribution, we need the protections of the GPL.

If I could flick a switch to turn all OSS projects to GPL, it'll impact the entire industry in a good way. OTOH, changing everything to permissive licenses will have absolutely no impact.

Just a minor nitpick, but adding a GNU license to the code base do not mean you have to change the license. The distribution of a code base that combines different licenses must simply follow each and every condition of the compatible licenses.

The effective license will of course look very similar to the GNU license, since following the GNU license conditions will most of the time also mean that you are in compliance with the permissive licenses conditions, but there are exceptions. For example, GPLv3 do not forbid distributors to use the authors names in the promotion of products, but it is compatible (under the additional terms section) with 3-clause BSD that explicitly do forbid such promotion.