The regulation was written in time when there were no such devices. Are they "healthier" (less damaging) for the user? If yes, let's tax them lower. Are they less damaging for whole population? Considering the e-waste, I guess not, but it's not up to me to decide. If they aren't, they shouldn't be taxed higher that cigs, if yes, let's change the regulation.
Because they contain so much more nicotine they are way more addicting, way better for the lungs than smoking but still bad for cardiovascular health. Disposables should be illegal for environmental protection reasons, that's a bit unrelated though since these companies can very easily switch to reusable/pod-systems.
We want people to vape rather than smoke tobacco, obviously, it's not a zero-sum issue.