From a practical standpoint, I can't come up for a reason to have a one man tent over a bivy (which is what I also use when I'm fastpacking, etc. - Custom camo Bibler $$$), but I certainly can see the practicality of using a 2-person tent, especially when going moto-camping. I'm just not all about leaving my gear on the muddy ground during a rainstorm - and I learned this the hard way! :-(
My moto-tent was purchased from a big box store for something close to $50. It can hold 2 adults comfortably, is rectangular 2-crossover pole design and about 1/3 no-see-um screening (obviously a 3 season tent), but great for ventilation and keeping the bugs out/seeing the stars. I haven't purchased/built any shorty aluminum poles for it so the thing would be more compact and light, but for little more petty cash, it may be worthwhile to do this.
I guess it just depends on what you want and what you plan on doing with it.
In mountain country (where there are very few flat spots) you also might consider this:
http://www.mosquitohammock.com/ Which can be also be ground staked.
Life is short. Eat, Drink & Be Merry!