I finally got it threw my thick skull that the poor things are weak health wise but are a great way to keep your base safe. Anyone have a good way of using them besides putting on the front line or putting them behind your militia causing friendly fire?
Shield them with sandbags. Plus some walls if you don't mind blocking the turret's line of fire along a particular line of direction (like say, at the back or at the sides where your colonists are located). I find diagonal wall sections useful (behind the turret) as it still allows colonists to repair the turret through the diagonal gap while shielding them from turret explosions.
(Remember to add power conduits if you build walls near turrets though. Otherwise, the turrets will draw power from the unpowered walls and stop working.)
You can also use colonists positioned at an oblique angle to draw some aggro. They should last longer than the turret if they have good cover.