How is that any better, you still have a bearing that can seize once it gets worn out. Looks like a pretty small bearing at that.
The bearings on the spindle kit are standard-sized wheel bearings. They have two benefits, one, they are spaced further apart and are closer to the center-line of the wheel, supporting the weight on the spindle, instead of the end of the axle stub shaft.
Two, they are easily serviceable, well, serviceable period. I can (and will) carry a set of pre-greased bearings and a seal with me. All it takes to change them out is an allen tool and a spindle nut socket. In a pinch I can use a hammer and punch to get the spindle nuts off and back on.
Can full floating bearings also fail? Yes. I had a set go out on my old '78 Bronco while driving down I-75. Difference is, I felt the wobble in the steering wheel and pulled over before anything came loose. Everything inside the wheel hub was destroyed, everything from the steering knuckle out had to be replaced. But the wheel did not come off, the wheel did not collapse under the front end, the vehicle was in no danger of losing control and endangering others. I was able to get home simply by gutting out the inside of the wheel hub, putting in new bearings, and driving home. Just a couple hours work in a gas station back parking lot. Got home and then replaced the axle stub, spindle, bearings, seals, brake rotor, caliper, pads, and locking hub. A lot of work but I was at least able to drive the truck home.
Unlike the unit bearing, which can, has, and will fail without warning, sending the vehicle seriously out of control.