I think it depends on the person. On the other hand I think we all have some issue with heat because most of us grew up with it being used in unhealthy ways. We're conditioned to think that more heat is better because, surprise, most of us had to sit at the stove and get our hair pressed before it became remotely presentable.
I used to think I had the heat under control but in reality I didn't. I didn't realize that with proper tools and techniques, I could get the sleek straight and shiny styles I wanted without all the heat.
I wonder how my hair ever grew with all the heat I was using. And then I understood why my hair would grow good and then some small thing would cause a chain reaction of breakage and damage.
I haven't used heat on my hair since Sunday. I haven't flatironed it and I don't own a curling iron. But you would never know by looking at my hair. Its very straight, very shiny, and has bounce. I wrap it every night and use quality products (read: Joico
).
I wouldn't say that heat is so much bad, or good as it is necessary. If you do not have naturally straight hair, the easiest and probably the fastest for most of us is to use heat.