Is there any reason not to decrystallize honey?
I'm just a humble beekeeper.  I went about my business doing what I do, ignorant of other ways or ideas.  I sell my honey at a local food co-op, being the only local beekeeper who can meet their demand.  I did a taste-tasting event one day where I got to interact with those who buy honey.  WOW! What an eye opening experience.  There were folks who would not ever consider buying my honey because it was liquid (I just harvested it three days ago!) and instead opted for the "raw" honey that had traveled thousands of miles and through various customs agents to get to their shopping cart.

Bees make liquid honey.  Honey naturally crystallizes. Not all honey crystallizes at the same time. As a relatively small time beekeeper, I extract all my own honey.  I get it from the bees, and spin it out a few hours later.  I keep the room I extract in a balmy 80 degrees and have no problem extracting it or bottling it at this temp.  I have never even heard of "heating" my honey to extract it... I guess the HUGE producers have to do that, they don't tend their own bees, but contract with commerical beekeepers.  They are harvesting days to weeks after the honey has been taken from the bees.

In summertime a beehive can easily be over 100 degrees inside.  Yes, it can be over 100 degrees where the honey is when the bees have it.  I call this the biological norm temp.

The previous responders were right in that compounds in the honey do denature when it's heated.  I couldn't find the link, but there is a good article on the half-life of enzymes in honey at various temperature... at high heat, they can disappear quickly.  But at temperatures below 110, they are relatively stable... at 90 even more so.  If I need to decrystallize honey, I stay around 90-100 degrees and decrystallize slowly.  Again, 90-100 degrees is within the biological norm for honey; I don't feel I compromise the integrity of my honey with heat.

P.S. There is no USDA definition for "raw honey".  As a beekeeper, I find it a meaningless term.  One person could live in a climate where he harvests and bottles at 100 degrees, and another could harvest on day that is 60 degrees, but heat her harvesting and bottling area up to 90 degrees.  Is his "raw" but hers not raw because she heated her working space?

P.S.S.  Buy from small time beekeepers... they don't have the fancy equipment to heat or "cook" honey.