You are wrong. History tells us that size is an intimidation factor....a huge one. That was exactly the reason for the size requirements. Other than being argumentative. You know, I run into this a lot.. People arguing for arguments sake. No valve. They just get pomade by logic.He answered the question in post 87, so let's not pretend that anyone is dancing around questions.
Is it surprising that a unit that was used to protect the emperor and his family was expected to look the part? No, of course not. Any emperor wants his guards to look intimidating and give the appearance of being elite. Note for example that epitaphs indicate that Praetorians were much more obedient when it came to the law that active soldiers could not marry. It was about appearance and group identity.
But does that mean that an extra two inches made them any more intimidating to a senator than any other military unit? I doubt it. A soldier with a weapon is as intimidating to a civilian as the next soldier. Did it make the praetorians appear intimidating to a field-army or frontier unit? It seems unlikely. As far as I can tell, there is no evidence for such a unit declining to face the praetorians in combat, and why should they have declined combat? Because of an extra two inches? We have evidence for prejudice in the Roman world towards soldiers who spent excessive amounts of time in cities and in peaceful regions. The Praetorians fit both of these criteria. This doesn't jive well with the idea that they were intimidating for other soldiers. We know of Praetorians fighting in civil wars for Otho, Vitellius, Didius Julianus, Macrinus, Maximinus Thrax and Maxentius, and none of these instances support the idea that other military units were afraid to fight them. Indeed, the Praetorian cohorts were on the losing side in each of these encounters, and in the case of Maximinus Thrax the civilians of Rome attacked the Praetorians and tried to sack their camp, initiating hostilities.