How are they intended to be used though? Seems to me they are designed to be addictive.
Well...technically they are designed to be enjoyed...but yes they are very addictive too. And while that doesn't mean that smoking a cigarette will get you hooked, it does mean that smoking them is pretty dumb if you want to avoid getting addicted. Dumb, but still not a sin in and of themselves.
I think this distinction is important and here's why. I grew up in a church that believed...
*it was a sin to let a boy kiss you....when in fact it wasn't but rather it was something that they knew could lead to sin.
*it was a sin to dance...when in fact it wasn't..but etc etc.
*it was a sin to go to movies...when in fact it wasn't unless you were watching sinful movies (and in fact was an attitude that handed the whole industry exclusively to the devil on a silver platter).
This difference is called legalism...and its an important difference for a number of reasons. One is learning where you need draw the line for yourself. Another is the tendency to throw out the good with the bad when you realize you were being lied to. And...most important of all...legalism is a sin. It was was the Pharisees did that Christ preached against.