Born in Colorado, finished school in Arizona, did 5 tours in the jungles of Panama. Started camping while in diapers. Always slept on the ground, never had a bug or scorpion attack. I was bitten by a rattler but not while asleep. I guess if you have bug or animal phobias a rtt may help.
I'm with you on this one. On many occasions with the army I've had to basically roll out of my vehicle in the middle of the night straight into high grass (2 meters +), roll out my mat and sleeping bag/bivvy and throw over my mozzie net. No time to worry about snakes, spiders and every other potentially lethal reptile (crocodiles come to mind) or insect wanting to kill you here in Australia lol. Not once have I ever been bitten (hope I haven't jinxed myself now) or had to worry about it. We often sleep under a hoochie (small tarp) as well if sheltering from rain. But as you said if you have a phobia then maybe an RTT would probably be better suited to you. The military does toughen you up though particularly when you don't have a choice in where and what you do. :)