I think people differ in their use, here's a couple of examples of what I mean by that:
* I always dry grind my tools right to the edge of the hollow, like the very edge, as in three swipes on a 1000 grit stone brings a wire edge. On a good carbon steel chisel, I almost lament how much metal that will remove, esp. if the stone being used is a semi fresh diamond stone. It literally takes less time to hone off of the dry grinder than it does to put a tool in the tormek jig and take it back out, and the dry grinder time is less during the grinding process.
* I never have water at my grinder unless I'm doing something really heavy. I check for temp and cool an edge by dragging the back flat side on my palm. If I can stop whatever I'm dragging in the middle of my palm, it's not that hot

The other real turnoff of the tormek, aside from the water, and aside from the fact that the black wheel essentially could only be graded by diamonds, and the gray wheel needed to either be refreshed or diamond trued to cut fast, was that the cut speed was never very consistent (you'd love to have it aggressive all the time, but it constantly breaks in like any hard stone, unless you're sharpening something narrow on it, and that just puts lines in the wheel) and putting something like muji HSS on the stone just graded it right down.

Freehand grinding can be just as even as the tormek, except you don't try to raise a wire edge with it, you go just short instead. Not that raising a wire edge necessarily causes temp. problems on a coarse wheel, it doesn't, but it does cause geometry problems because the wheel is narrow.

And, if the purists would look away for a second, I have ground japanese tools on the dry grinder without any issue. I don't do it often because it's totally unnecessary, but I do have a coarsely set funjii plane (an inexpensive but fabulous little beat-around plane that JWW no longer sells) that I use as a jack that gets refreshed either by a belt grinder or a dry grinder.

Certainly for someone who is new, a tormek would be better for japanese tools if there is some large correction to be made or a bulge in a bevel to get rid of or some other such thing.

But, to paraphrase what warren says, if someone has trouble using a dry grinder faster than it's possible to use a tormek, then the dry grinder hasn't yet been mastered.

In this case, a turtle is a turtle. And my turtle is now in a celebrity's shop in virginia.