It gutted it, in the sense that we've been operating under an interpretation of the law for the past 20 years and this ruling changes that interpretation dramatically. The law wasn't so much badly written, as technology has completely changed in the time since then.
As an example, if this law were written today, I'm not sure that cell phones would get special status. They were put in the same category as medical emergency lines, because "radiotelephones" were very rare and expensive to operate, whereas today every 12 year old has one.
No, the law was badly written, at least if the goal is to limit all robocalling and not just robocalling using sequential or randomized numbers.
The law essentially says "it is illegal to call someone using an autodialer, where an autodialer is a device that makes calls to phone numbers using a sequential or randomized algorithm." It's pretty clear then that automatically dialing from a prepared list of actual phone numbers is not against this law. If they wanted it to cover the latter case, they could have easily included that in the law, even 20+ years ago.
As an example, if this law were written today, I'm not sure that cell phones would get special status. They were put in the same category as medical emergency lines, because "radiotelephones" were very rare and expensive to operate, whereas today every 12 year old has one.