I don’t understand why everyone moved away from directly smoking the flowers so readily. I hated the idea of shatter/resin when I first heard it and there is no way I would use a vape pen.
Vapor, on the other hand, (theoretically) contains only 3 chemicals: glycerin, propylene glycol, <nicotine/THC/active stimulant>. In practice though, vapor has probably thousands of compounds as well due to "flavors", additives, and side effects of the heating coil on those things.
It's all about perception though. Lighting something on fire and inhaling smoke is perceived as dangerous compared to inhaling "vapor" (which everyone does every day in the shower, right?)
No recognizable smell. You can carry a pen with you, hit it at your leisure, and there's no burning flower smell, no through the bag smell, etc. It's much more discrete, so it's easier to possess, use, and conceal.
Assuming legit products, it's often a better deal as you know what strength you're getting and how much mileage you get out of it.
That said, induction-based direct vaporization of dry flower is the best of both worlds.