Regulatory structures can be pretty fraught if you go beyond the standard Consumer Guarantees Act protections. They all sound nice, but can wind up being a mess.
Put in requirements that each product be approved and you'll kill off any innovation in creating new flavours as each would need a separate costly approval process. Let the public health ideologues lock them up behind prescriptions and you make it that much harder for real-world smokers to make the switch. And taxing them both discourages switching and complicates retail availability.
Watching the public health establishment's response to a massive technological change that promotes harm reduction but that doesn't run through channels where they can clip the ticket along the way, and that also lets people enjoy psychoactive and addictive substances without deleterious health consequences, has been interesting.