To use, modify or redistribute GPL software is not a rip-off. Rip-off implies something ilegal. If you are impeding the freedoms guaranteed by the license, that is a rip-off.
You were less wrong using “unethical” term since ethic is a grayscale zone and can be discussed.
You should keep in mind that you can write plugins for a lot of people just because the GPL ecosystem built a very big community of users. All this people adopt this ecosystem because they can feel it as their collective property. If you do not respect the terms of the GPL you are damaging that ecosystem. Wordpress is clear about it: “If you disagree, you might want to consider a non-GPL platform such as Serendipity (BSD license) or Habari (Apache license) instead.”
So, although I am not a friend of opportunism and I don’t like those GPL clubs, the dilemma is between two choices: To preserve the ecosystem or to preserve your personal profits. I understand that personal profits of software development are very important to software developers, but it can’t be defended with ethical arguments against GPL terms.
A metaphor: think in a lumberjack in the forest. He can persevere their profits against forest environment. If you, as a developer, make GPL software, you are seeding more trees in that forest. Otherwise, you are the lumberjack.
So, how can I survive as a developer in a GPL environment? This is a complex discussion and I’m afraid it exceed the topic of this forum. Anyway, it includes concepts like “real time economy”, “attention economy” and “economy of services”. I will be happy to discuss this further if you deem it appropriate.
Just to say that, in wp-sync-db case, I prefer clearly to buy a complete functional WP Migrate DB Pro plugin, and avoid to hack trellis to adapt it to wp-sync-db needs, but my personal situation is very hard, actually, without resources to cover my basic needs. So, to find free resources is mandatory until I get afloat.
So, unlist my previous thread was a bad decision:
https://discourse.roots.io/t/can-i-downgrade-composer/9703
Because this decision was completely based on a arguable opinion and, in strictly sense, it can be considered censorship. This kind of decision hurts me since internally I’m involved with the roots community (despite my low level as a front-end developer). I learned a lot and I got huge satisfaction here.