Your choices and defensibility are somewhere limited. You can't deploy anything in a plasma storm and no strike craft in the ion cloud. I normally see space junks at the end of a phase chain (probably coincidence) and asteroid belts have the debuff, but could still be somewhat useful in delaying an enemy. You also wouldn't get your factions bonuses that require you to be in friendly territory outside of a culture buff. Lastly I think more often than not it would just be another way feed an enemy titan.
However I think it does have potential to be a sort of "pit stop" since you can already construct frigates / cruisers along with platforms or a phase inhibitor if being pursued through it.
Also forgot... GOD FORBID it's a minefield between planets....