I had a cheap wire brush explode on me many years ago when I worked in a shop. I looked like I pissed off a porcupine. Bristles were stuck in my clothes, my arm, and my face. Fortunately I wore safety goggles or I'd probably be half blind. One entered my face just below the goggles. Had a no-name cutoff wheel explode back then too. Took a chunk to the cheek.
I only buy USA made wire wheels and abrasives. I'd venture into Japan or certain parts of Europe if I absolutely had to.
Edited since I made a bad mistake on the rpm and diameter scaling (reversed; worked in head and was wrong -- duh!) This version is fixed.
Some tips to reduce concerns:
* Use good quality wire wheels and discard them after a significant number of hours or they show sign of deterioration (hard for cheapo me to do). A wire breaking off can be a sign that a lot more are ready to break.
* Of course always wear protection, especially for eyes, with wire wheels. Goggles or a full face shield are best. A heavy leather apron also helps. Plus leather gloves.
* Use them on relatively low rpm buffers or grinders with smaller diameter wheels. Yes, this means the work takes longer. But it is way safer. The centrifugal force acting of the wire is proportional to d x (rpm)^2 where d is the diameter of the wheel and rpm is the rotations per minute of the wheel. So larger wheel diameter linearly increases the force. But the force increases with the square (rpm x rpm) of the wheel rotations per minute. So wheels generate much more wire stress quickly as rpm increases. A smaller diameter wheel on lower rpm has dramatically less wire stress translating to dramatically more safety margin. Go lower rpm with smaller wheels and live with slower progress.
Stand a bit to the side of the wheel in case something breaks or the wheel snags a work piece and throws it (another danger).
If you do these the likelihood of a bad mishap is greatly decreased and you can use the wheels with much less stress. Handheld wire wheels on angle grinders probably need even more care in use.
Hope this helps.