I'm more a tent person myself, but a lot of people I know own both and use the swag more often.

The main benefit to a swag is you can toss it in the back of the ute, drive to your campsite, roll it out, and drink a beer while watching your friends setup their tent, pump up their mattress, etc. Which is quite entertaining, because if there's one thing I've learned in years of camping it's that I seem to always be the only person in the whole group who actually knows how to setup a tent properly.

If it's windy, or raining, most people are going to be comfortable in a swag and have a horrible night in a tent. The tent is more comfortable if you set it up properly, but apparently that's too much to ask...

And when it's time to go home the next morning, you'll be done packing up your swag when the tent people have finished rolling up their sleeping bag.

Personally I don't mind the extra time to setup my tent and appreciate the extra room (we usually take a ten man tent for three people... though we also have a four man tent). The setup/pack-up time is just part of camping.

The other advantage of a thick canvas swag they last forever. I consider myself lucky if a brand new tent lasts even two or three camping trips without a hole somewhere. You can buy canvas tents but holy batman those are heavy!