For me, as a native speaker, i don't see any compelling reason as to why it's "fläskköttet" and not just "fläsk". For example saying "Jag äter fläsköttet" instead of "Jag äter fläsk" just sounds weird to me. If you were to discuss different types of meat it would be more appropriate, but in an everyday conversation it just sounds unnatural to me.
thanks for that detail, I thought it looked and sounded unnatural. I couldn't imagine a native speaker wanting to add additional syllables to something that ideally comes up in the context of food or meat. My question would be, is that true for beef as well though, because nöt means nut