Open Source is a marketing term, coined by ESR because "Free Software" is scary to businesses, much the same way that record labels coined 'New Wave' to make Punk Rock palatable to the record buying public.
That said, "Open Source" became polluted too. I have seen comments here say "Open Source vs commercial software". Oops. Anyway, in my language, we don't have this issue: we have two very distinct words to distinguish freedom from gratis, so the issue didn't come up in the first place (at least when we avoid English).
But careful examination of the semantics actually reveals (1) errors, (2) biases, and (3) contradictions. Which - as a blunt stereotype - is where hackers will excel, the technical & careful examination.
Engaging the idea directly: rms is a zealot. His goal is libre software as a grand moral good. He is a ideologue from the 1970s, with all that should connote. This will not make the modern ironic zeitgeist comfortable. I don't know why anyone should expect otherwise.
No, Open Source is a properly defined contract that compatible licenses must comply with.
On Free Software, even though the GPL from a legal standpoint is one of the best crafted licenses around, especially version 3, the definition of Free Software is intentionally confusing because the decisions made on what constitutes Free Software or not is made by a committee driven by RMS's ideas about what freedom is, depending on his mood.
This is not to say that OSI doesn't make mistakes. AGPL was accepted as open-source, even if it shouldn't have been, probably because they wanted to avoid even more political battles.
Also, many companies and individuals that are working with licenses such as GPL or AGPL are doing so for dual-licensing, especially in cases where the software otherwise is useless without a proprietary option. Lets not forget that Gnome was born because of KDE's dependence on Qt, as companies couldn't build proprietary or otherwise GPL-incompatible software without buying Qt licenses (and btw, APL is incompatible with GPLv2).
And personally, I prefer Tolvards' views on what freedom is, rather than Stallman's.