Besides, ounce for ounce, tents that require you to set them up with stakes (i.e., "non freestanding") are sturdier than their freestanding equivalent. So go figure.
Why are freestanding tents so popular, then? Well, for one thing, they're much easier to set up in a camping store showroom. And there is a convenience factor—it's easier to set up a tent and simply stake it out to support the vestibule and pin down the corners than it is to set up a tent where you really have to pay attention to the stakes and how they're placed. So I understand their appeal. Myself, I use both types—for lightness, though, non-freestanding models usually are best.
For three-season camping, typical freestanding tents include the MSR Hubba Hubba ($280, www.msrcorp.com), the Sierra Designs Comet (maybe the classic backpacking tent; $300, www.sierradesigns.com), and the Marmot NYX ($269, www.marmot.com). All are two-person, three-season tents that weigh in the five- to seven-pound range, set up easily, and offer excellent protection from the elements along with plenty of ventilation.
In the non-freestanding category, I like Mountain Hardwear's Waypoint 2 ($250, www.mountainhardwear.com), which weighs just over three pounds but holds two people comfortably. Kelty's Crestone 2 ($140, www.kelty.com) has a similar design, but uses a little heavier materials so weight is just over four pounds. Both require solid stakes at the fore and aft ends, and the tension from those placements allows a center-arch pole to handle the job of creating interior space.
The best tents, freestanding and guyed-out, reviewed in Outside's 2004 Buyer's Guide .