probably slept outside more than most people on this board because of my hitchhiking hobo years so here's some experienced advice
tents are comfy. help against weather, keep critters off of you, acts as a barrier against larger animals, strangers are wary around them if they cannot see inside. when the weather is nice, the tent's main function is security of mind, procuring restful sleeps. I've slept in the open plenty and in tents plenty, sometimes the difference is several hours of sleep lost without a tent. an A-Frame tent ain't shit to carry on a hike, and I've set that shit up in less than three minutes in pitch-black darkness before. I consider it a high priority accessory, more important than a knife. more likely to save your life than a knife is. not that there's any reason to not carry both, just putting into context how important I think tents are. sleeping bags are another story though unless you're somewhere with the potential for cold weather, in which case you should always carry a sub zero. better to be too hot and lying in an open bag than too cold. 'sides, open bag is comfy when you're in a tent. very little reason to not bring a tent on a camping trip. romantic ideas about the open air, 'muh ultralite', okay dude. I'll feel comfortable and secure and get a great night's sleep while you do that.
