I would never consider one of these - or any other form of piercing.
In trying to understand those who get an anal piercing, what's the motivation?
Stimulation for the wearer during penetrative sex? Perhaps for some, but the photos in the link don't reveal that all of them are proximate enough.
Stimulation for your penetrating partner? Maybe, especially for the "inside" ones - which are also the most potentially problematic, even with rivers of lube.
Passive stimulation while wearing? Maybe. If you're a horseback or bike rider (YIKES!), gym rat (spinning, weight lifting), or even play racket sports ("what's that clicking noise?") I think there would be trade-offs, at best.
Mental stimulation? Probably/certainly. But they're certainly NOT ornamental to be seen when out in public unless you're a nudist and an exhibitionist.
Depending on the number, gauge and retaining ball size, would these trigger an airport security scanner? Especially the newer ones? I'm sure THAT would be an interesting pat down and "show and tell" with TSA!