The whole point is that these are kids who wouldn't be using nicotine products at all. Smoking rates have declined in the US over the last 40 years, and yet there's been an uptick in youth nicotine usage since the introduction of e-cigarettes.
So when talking about youth usage, no, this is clearly not an improvement, by any measure.
i.e. Why is nicotine so much worse than THC, alcohol, caffeine, guarana, or any number of other stimulants/depressants?
Alcohol and THC are both already restricted to adults. Caffeine is restricted as well, in that many places won't sell caffeine pills to people under 18.
Nobody is talking about preventing kids from buying tomatoes. But when we're talking about concentrated and extracted forms of a stimulant... those are already heavily restricted.