it depends on the drummer, but in a lot of cases...especially if they record themselves or do a lot of studio gigs, i think it is intentional to play less to focus more on the groove, music. Steve Jordan is a perfect example & he plays studio gigs on guitar, bass & drums. so he definitely plays for the music & groove...what the other rhythm players want from a drummer.2) Why do certain drummers, like the Coldplay drummer, do nothing? No fills, no nothing? While playing, sometimes I can just "feel" that there is a fill there, and I do my own thing, and it sounds good (not my execution itself, but the element within the song...). Is it a concious decision by the drummer that musically it makes sense to do nothing, or is it a skill limitation?
i also feel like you might be getting at "how do these guys play so simply but still nail the time, breaks, simple fills & groove ?" in general, they are constantly moving / swaying / dancing / bobbing their heads to the time. i.e. the time / groove doesn't stop just because there was a break.