As it turns out, the Agents of S.H.I.E.L.D. adventure into space actually happened because it was the last big thing that S.H.I.E.L.D. hadn’t done.
Season 4 was broken up into three arcs, or “pods,” that saw three complete stories begun and ended.
According to Jed Whedon and Maurissa Tancharoen at the recent WonderCon convention, space was different enough for the show to send the characters to kick off Season 5.
While it was a fun change of pace to watch the show move through stories at a quick pace without any filler episodes, it also meant that S.H.I.E.L.D. was relatively quickly moving through plots that could conceivably have been stretched out into a full season.