FOSS has always been about “free as in speech”,

If you're being pedantic, then yes, because Stallman coined "Free Software" as a term and that rolled into the acronym "FOSS". If you're talking about what we actually thought, then no.

FOSS vs. proprietary is tangential to the discussion over filesharing, anyway, because it addresses different issues. FOSS isn’t good because it’s zero-cost, it’s good because it respects user freedoms.

From a totally different angle, it's good because it does more to empower innovation and creative expression than IP ever did, yet innovation and creative expression were always the stated goals of IP. Because of that, it's a lot less tengential a discussion than things like filesharing, which also empowers creative expression. Cost-free, unlimited access to art is the best way to get art in the hands of everyone. And that is "free as in Beer".