why has no one considered Blu?
Because in 2015 its less about the hardware than the software. Those phones come with Kit Kat 4.4, and might never get 5.0 let alone the 5.1 that fixes 5.0. Plus Blu's Android skin is
DISGUSTING, it is that worst case Miui-type skin that is just a crappy copy of iOS in too many ways (aka no app drawer). It is nothing like stock Android, and we are an enthusiasts forum.
We are now to the point where many Chinese/foreign focused companies like Blu and Xiaomi and whoever offer a lot of good hardware value for the money, and then ruin the software experience for an American audience. These cheap phones are designed with a foreign audience in mind who care less about updates (because they might have problems getting them anyway) and more about aping the ultimate status symbol called the iPhone.
We do get excited about the crossovers, aka the companies that try to play ball with western enthusiasts. Like the One Plus One or the Micromax YU Yureka that both ditch the disgusting skin for CM. Or how excited we will all get about the Huawei Nexus if it happens. And I think the success of these devices will bring more devices. The problem is that many Chinese OEMs haven't proven they have a software side that can crank out a nice stock Android without bugs, while CM is about to ditch the parts of Android that a lot of us care for.
For "normal" people a Blu phone isn't fine because no one has one, which means no support or buyer validation. For normals the problem is less about the OS (which they don't know about) and more that they can't bug the poor people at the Verizon store when they have problems with the device.
Honestly these cheap phones are spinning their wheels. They sell on specs, something normals don't care about, with a crappy OS, which makes enthusiasts who care about specs tune out. It reminds me of when American-centric companies go into non-US markets and assume that everyone's taste is the same as Americans.
People point to the ROM community, but except for major devices most don't get third party AOSP Roms. And even with the major devices those ROMs are hacks. If its not stable to the point of a Nexus ROM or a GPe ROM why bother? Who cares how many megapixels the camera has if the ROM breaks HDR.