Without it though you're exposing the pedal to the bolt heads of the adapter plate which is far more likely to damage stuff. Look at your top pic - looks like it's already eaten away some of the bolt head.
They also keep the lube where it should be and it would stop stones or anything getting in the gaps where the bolts are if, heaven forbid, you had to walk somewhere dirty.
They are for 4 bolt shoes, so you don't wear out the base of your expensive carbon shoe. If you are using the 3 to 4 bolt adapter then that is easily replaced instead - or that's the idea anyway.
I've got the extender plates on mine. I still think the smoove, shiny metal base is a better idea then gaps with bolts and shit sticking out. But whatever floats your boat. Everyone is free to be wrong about stuff :)
Without it though you're exposing the pedal to the bolt heads of the adapter plate which is far more likely to damage stuff. Look at your top pic - looks like it's already eaten away some of the bolt head.
They also keep the lube where it should be and it would stop stones or anything getting in the gaps where the bolts are if, heaven forbid, you had to walk somewhere dirty.
Get some. Make Jesus happy.