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The problem is this: general consumers don't understand how and when to use bivies so they just buy them for general camping or backpacking. The main advantages of a bivy all come from its use in mountaineering. Not all of those advantages also apply as advantages for general camping situations. Really, all you’re getting is something that’s a tad easier to set up.
The following are the main disadvantages:
>1. It's extremely cramped inside (no room for gear, and when it’s raining, you’re stuck in there).
>2. There is no space between the waterproof material and your sleeping bag, so any condensation that forms inside will transfer to your sleeping bag's shell material immediately.
>3. You cannot get in and out of one in the rain without the inside getting wet.
>4. etc.
I could go on, but already we're dealing with a shelter, whose sole purpose is to keep you dry and comfortable in the rain, which is neither dry nor comfortable in the rain.
You can mitigate disadvantage #3 with a tarp, but we’ve lost your ease-of-use advantage.
You'd think that there would at least be some sort of weight advantage over the other options, but the opposite is often true, at least with the ones (read: bivy tents) you’ll find at REI. The OR Alpine Bivy pictured in the OP weighs in at a whopping 2 pounds! That's heavier than some double-wall tents (see: Big Agnes Fly Creek tent, 2lb 3oz for the two-man version).
It makes little sense to me why someone would willingly choose the option that more resembles a coffin when the weight is the same. Compared to other shelter options, like a tarp or even a tarp-tent, the bivy tent (exemplified by the OR Alpine Bivy) is not only smaller, but significantly HEAVIER. A solo-sized tarp made out of silnylon would typically weigh 11-13 oz with stakes incl. and will provide MORE floorspace. If you're interested in carrying 2 pounds of tarp and stakes, you can get at least 9'x9' of floor space out of a larger tarp, which is huge!