Alzrius
The EN World kitten
I'll make a fairly large generalization, since both D&D and anime have wider ranges than their stereotypical depictions, but in my experience this comes down to D&D being thought of as comparatively low-power fantasy whereas anime is often noted as being high-power fantasy.Not sure if this is a false-construct or if anything to it, but I seem to notice that I have my anime friends and I have my D&D friends. The guys/gals who are into anime seem to have a different preferred aesthetic than the ones who gravitate toward D&D.
Exceptions to those characterizations are numerous, of course, but I think a lot of people still look at D&D as "Conan and Gandalf team up to fight Dracula," whereas anime is often viewed as "lots of loud screams as energy blasts are fired, dozens of punches are exchanged in seconds, and massive explosions change the landscape."