The whyI normally like scale-looking things. For multirotors, that doesn't make a lot of sense, but I still like the enclosed body look over the open frame, let it all hang out look popular for miniquads.
The downside of this is that you have a battery compartment. For larger multirotors, this isn't an issue - there's lots of room, and a switch won't add much weight. But for the 200QX, getting the battery in is a squeeze, so using even a slightly larger battery won't work. And the battery cover is under a bit of pressure for the 3C battery Blade recommends for it.
So when my 200QX frame finally succumbed to my flying skills, I decide to try a miniquad frame replacement. Since I was going to put all the electronics on display, I decided to go with it, and got the Phoenix Flight Gear Polycarbonate Frame. I'm not providing pictures - they have lots of very good ones!