How can I choose to use a different operating system in my cellphone?
Say I discover that the software that controls my cell phone causes the processor to run at a frequency which has just been discovered (in one isolated, peer-reviewed scientific journal) to cause brain cancer. Other studies, which the manufacturer points to, seem to refute this idea, but being a lay science enthusiast, I believe the methodology and conclusions of the more recent study to be sound.
I do not want brain cancer. I did not choose to purchase the software which now threatens to give me brain cancer. The manufacturer doesn't believe (or doesn't care) about my wants with regard to cancer and their phone. I have the technical ability, if provided with source code, to patch the software to run the phone at a not-harmful clock speed. Being a kind person, I also am willing to redistribute my modifications at my own cost. But I can't.
I could choose to buy a new phone, but how will I know whether or not the software in that phone will similarly give me cancer? And why should I have to buy a new phone when I already paid my hard-earned money for the first one?
My point, if it's not already obvious, is that not all software is (and possibly in this embedded age, most is not) software purchased or downloaded by a person for use on a general purpose computer. And even of the software in that particular category, how many of the users of that software, if we were applying the same standard as for medical decisions, would we consider to be "informed" as to their options and the potential risks associated with each of them?
I think that while, as a software developer, Tim's argument has some selfish appeal, it's not really representative of the world we live in where most software is not some "work of art" produced by a talented individual which I can easily do without or replace. In that world, I think that moral choice between our selfish desires as individual developers (however rational an apparently benign) and the general good of people in general favors the FSF's position for all but the most "non-essential" software.