Just because you don't pay and don't want to pay, for something you believe to be flawed and generally, not helpful to anyone, that doesn't make it right or however you want to call it. I work in IT and I can tell you that, one way or another, we all pay for software that is flawed and not working as intended. But as someone said above, that's how things are. Of course, if you are unhappy and unsatisfied with it, you can stop using any kind of software, starting with the operating system. Even Windows is not perfect and although it got better along the years, and it's constantly being patched and fixed, it doesn't work flawlessly every damn second.
I use a free water calculator and it works fine. I fine tuned my process and know what to expect, which is why I make further adjustments on top of the water calculator, but fairly minor. ( acid qty )
I don't believ it unlawful, amoral or wrong to take donations or money for something, someone has been working on and still works on, to make it better, and in this case, provide assistance to brewers. You and I are free to pay or not pay for it.
But I suspect your real problem has nothing to do with the morality of selling/asking for donations for a piece of software, that does not give accurate results every time.