To prevent theft, I sometimes use soaker-style guards (with Kevlar at the bottom, so they last longer), and put them in my coat pocket. Not suitable for walking long distances, but they serve.
Rollergards are supposed to save time - presumably because you skate instead of walk from your car to the rink. I think that isn't all that large a time savings, so may be some hype.
With proper marketing, they might be as popular as Zucca bags. Imagine lots of little kids zipping around the parking lot, up and down the banisters, and around the lobby of your favorite ice rink. Much more fun than trying to clumsily roll yourself around on the Zucca. Not that that will be altogether safe, especially without a brake.
And perhaps aggressive in-line skating could damage a figure skating blade or loosen its mount.
But they do look fun!