If you only take, obviously there is no reason to complain. Now the problem is rather when contributors (those who "give", not those who "take") have to sign a CLA. Then the company who gets their copyright takes their work for free, to later use it in a non open-source project (assuming they changed the license, like Redis did).
I think it is valid to find this immoral. The solution is pretty simple though: do not contribute to open source projects that require you to sign a CLA.
I think it is valid to find this immoral. The solution is pretty simple though: do not contribute to open source projects that require you to sign a CLA.